diff --git a/README.md b/README.md
index 56d82f0..d1620e5 100644
--- a/README.md
+++ b/README.md
@@ -28,3 +28,4 @@ How to use:
  - Step 4: set Wifi information, save & reboot. Fall back to AP mode if WiFi connection fails (AP password sets to default SSID name from step 2).
  - Step 5: find the device IP with last 4 character MAC address in your router
  - Step 6: (optional): Set MQTT information for use with Home Assistant
+ - Step 7: (optional): Set Login password to prevent unwanted access in SETUP->ADVANCE->Login Password
diff --git a/src/mitsubishi2mqtt/config.h b/src/mitsubishi2mqtt/config.h
index 2000338..c8c6466 100644
--- a/src/mitsubishi2mqtt/config.h
+++ b/src/mitsubishi2mqtt/config.h
@@ -3,12 +3,12 @@
  *
  */
 
-String m2mqtt_version = "0.4.8.1";
+String m2mqtt_version = "0.4.9";
 
 //Define global variables for files
 String wifi_conf = "wifi.json";
 String mqtt_conf = "mqtt.json";
-String advance_conf = "unit.json"; //we can use advance.json but keep old name for backward comparity with version 0.4.8
+String advance_conf = "advance.json";
 String console_file = "console.log";
 String others_conf = "others.json";
 
diff --git a/src/mitsubishi2mqtt/html_common.h b/src/mitsubishi2mqtt/html_common.h
index 89c1811..6f83421 100644
--- a/src/mitsubishi2mqtt/html_common.h
+++ b/src/mitsubishi2mqtt/html_common.h
@@ -1,4 +1,4 @@
-String html_common_header = R"====(<!DOCTYPE html>
+const char html_common_header[] PROGMEM = R"====(<!DOCTYPE html>
     <html lang="fr" class="">
     <head><meta charset='utf-8'>
     <meta name="viewport" content="width=device-width,initial-scale=1,user-scalable=no"/>
@@ -27,7 +27,7 @@ String html_common_header = R"====(<!DOCTYPE html>
   </head>
 )====";
 
-String html_common_footer = R"====(
+const char html_common_footer[] PROGMEM = R"====(
   <br/>
     <div style='text-align:right;font-size:10px;color: grey;'>
       <hr/>Mitsubishi2MQTT _VERSION_</div></div></body></html>
diff --git a/src/mitsubishi2mqtt/html_init.h b/src/mitsubishi2mqtt/html_init.h
index 583c4b5..912a1e8 100644
--- a/src/mitsubishi2mqtt/html_init.h
+++ b/src/mitsubishi2mqtt/html_init.h
@@ -1,4 +1,4 @@
-String html_init_setup = R"====(
+const char html_init_setup[] PROGMEM = R"====(
   <body>
   <div style='text-align:left;display:inline-block;min-width:340px;'>
     <div style='text-align:center;'>
@@ -23,7 +23,7 @@ String html_init_setup = R"====(
   </fieldset>
 )====";
 
-String html_init_save =  R"====(
+const char html_init_save[] PROGMEM =  R"====(
   <body>
   <div style='text-align:left;display:inline-block;min-width:340px;'>
     <div style='text-align:center;'>
@@ -35,7 +35,7 @@ String html_init_save =  R"====(
 
 )====";
 
-String html_init_reboot =  R"====(
+const char html_init_reboot[] PROGMEM =  R"====(
   <body>
   <div style='text-align:left;display:inline-block;min-width:340px;'>
     <div style='text-align:center;'>
diff --git a/src/mitsubishi2mqtt/html_menu.h b/src/mitsubishi2mqtt/html_menu.h
index 2c67dbe..9cab7a4 100644
--- a/src/mitsubishi2mqtt/html_menu.h
+++ b/src/mitsubishi2mqtt/html_menu.h
@@ -1,19 +1,30 @@
-String html_menu_root = R"====(
+const char html_menu_root[] PROGMEM = R"====(
   <body>
+  <script>
+  var showLogout = _SHOW_LOGOUT_;
+  document.onreadystatechange = function(){
+    if (document.readyState === "complete") {
+      if(showLogout==0){
+        var element = document.getElementById("logout");
+        element.parentNode.removeChild(element);
+      }
+    }
+  }
+  </script>
   <div style='text-align:left;display:inline-block;min-width:340px;'>
     <div style='text-align:center;'>
       <noscript>To user Mitsubishi2MQTT, you need to activate Javascript<br/></noscript>
       <h3>_UNIT_NAME_</h3>
     </div>
-  <p><form action='/control' method='get'><button>Control</button></form></p>
-  <p><form action='/setup' method='get'><button>Setup</button></form></p>
-  <p><form action='/status' method='get'><button>Status</button></form></p>
-  <p><form action='/login?LOGOUT=YES' method='post'><button type='submit' name='Logout' class='button bred'>Logout</button></form></p>
-  <p><form><button type='submit' name='REBOOT' class='button bred'>Reboot</button></form></p>
+  <div><form action='/control' method='get'><button>Control</button></form></div>
+  <div><form action='/setup' method='get'><button>Setup</button></form></div>
+  <div><form action='/status' method='get'><button>Status</button></form></div>
+  <div><form><button type='submit' name='REBOOT' class='button bred'>Reboot</button></form></div>
+  <div id="logout"><form action='/login?LOGOUT=YES' method='post'><button type='submit' name='Logout' class='button bred'>Logout</button></form></div>
 )====";
 
 
-String html_menu_setup = R"====(
+const char html_menu_setup[] PROGMEM = R"====(
   <body>
   <div style='text-align:left;display:inline-block;min-width:340px;'>
     <div style='text-align:center;'>
diff --git a/src/mitsubishi2mqtt/html_pages.h b/src/mitsubishi2mqtt/html_pages.h
index 48c49cb..0dae3a6 100644
--- a/src/mitsubishi2mqtt/html_pages.h
+++ b/src/mitsubishi2mqtt/html_pages.h
@@ -1,4 +1,4 @@
-String html_page_reboot = R"====(
+const char html_page_reboot[] PROGMEM = R"====(
   <body>
   <div style='text-align:left;display:inline-block;min-width:340px;'>
     <div style='text-align:center;'>
@@ -14,7 +14,7 @@ String html_page_reboot = R"====(
 </script>
 )====";
 
-String html_page_reset = R"====(
+const char html_page_reset[] PROGMEM = R"====(
   <body>
   <div style='text-align:left;display:inline-block;min-width:340px;'>
     <div style='text-align:center;'>
@@ -26,7 +26,7 @@ String html_page_reset = R"====(
 )====";
 
 
-String html_page_save_reboot = R"====(
+const char html_page_save_reboot[] PROGMEM = R"====(
   <body>
   <div style='text-align:left;display:inline-block;min-width:340px;'>
     <div style='text-align:center;'>
@@ -43,7 +43,7 @@ String html_page_save_reboot = R"====(
 
 )====";
 
-String html_page_mqtt = R"====(
+const char html_page_mqtt[] PROGMEM = R"====(
   <body>
   <div style='text-align:left;display:inline-block;min-width:340px;'>
     <div style='text-align:center;'>
@@ -69,7 +69,7 @@ String html_page_mqtt = R"====(
   <p><form action='/setup' method='get'><button>Back</button></form></p>
 )====";
 
-String html_page_others = R"====(
+const char html_page_others[] PROGMEM = R"====(
   <body>
   <div style='text-align:left;display:inline-block;min-width:340px;'>
     <div style='text-align:center;'>
@@ -100,7 +100,7 @@ String html_page_others = R"====(
   <p><form action='/setup' method='get'><button>Back</button></form></p>
 )====";
 
-String html_page_status = R"====(
+const char html_page_status[] PROGMEM = R"====(
   <body>
   <div style='text-align:left;display:inline-block;min-width:340px;'>
     <div style='text-align:center;'>
@@ -117,7 +117,7 @@ String html_page_status = R"====(
   <p><form action='/' method='get'><button>Back</button></form></p>
 )====";
 
-String html_page_wifi = R"====(
+const char html_page_wifi[] PROGMEM = R"====(
   <body>
   <div style='text-align:left;display:inline-block;min-width:340px;'>
     <div style='text-align:center;'>
@@ -139,7 +139,7 @@ String html_page_wifi = R"====(
 )====";
 
 
-String html_page_control = R"====(
+const char html_page_control[] PROGMEM = R"====(
 <body>
 <script>
 function $_GET(param) {
@@ -268,7 +268,7 @@ document.onreadystatechange = function(){
 
 )====";
 
-String html_page_advance = R"====(
+const char html_page_advance[] PROGMEM = R"====(
 <body>
 
 
@@ -295,9 +295,8 @@ String html_page_advance = R"====(
         </select>
       </p>
       <p>
-        <b>Login Password</b>
-        <p><b>Password</b><br/><input id='lpw' name='lpw' type='password' placeholder=' ' value='_LOGIN_PASSWORD_'></p>
-        <p>Default user is <b>admin</b></p>
+        <p><b>Login Password</b><br/><input id='lpw' name='lpw' type='password' placeholder=' ' value='_LOGIN_PASSWORD_'></p>
+        <p>Note: Default login user is <b>admin</b></p>
       </p>      
   <br/><button name='save' type='submit' class='button bgrn'>Save & Reboot</button>
          </form>
@@ -305,3 +304,26 @@ String html_page_advance = R"====(
   <p><form action='/setup' method='get'><button class="back">Back</button></form></p>
 
 )====";
+
+const char html_page_login[] PROGMEM = R"====(
+<body>
+
+
+  <div style='text-align:left;display:inline-block;min-width:340px;'>
+    <div style='text-align:center;'>
+      <noscript>To user Mitsubishi2MQTT, you need to activate Javascript<br/></noscript>
+      <h3>_UNIT_NAME_</h3>
+      <fieldset>
+      <legend><b>&nbsp;LOGIN&nbsp;</b></legend>
+      <form action='/login' method='post'>
+      <p>To log in, please user : <b>admin</b> and password</p>
+      <p><b>User</b><input type='text' name='USERNAME' placeholder='user name'></p>
+      <p><b>Password</b><input type='password' name='PASSWORD' placeholder='password'></p>
+      <br/><button name='SUBMIT' type='submit' class='button bgrn'>SUBMIT</button>
+      </form><br>
+      You can go to <a href='/status'>status page</a><br>
+      <p>_LOGIN_MSG_</p>
+      
+  </fieldset>
+
+)====";
diff --git a/src/mitsubishi2mqtt/mitsubishi2mqtt.ino b/src/mitsubishi2mqtt/mitsubishi2mqtt.ino
index 1e49988..207671f 100644
--- a/src/mitsubishi2mqtt/mitsubishi2mqtt.ino
+++ b/src/mitsubishi2mqtt/mitsubishi2mqtt.ino
@@ -151,7 +151,12 @@ bool load_wifi() {
   hostname = doc["hostname"].as<String>();
   ap_ssid  = doc["ap_ssid"].as<String>();
   ap_pwd   = doc["ap_pwd"].as<String>();
-  ota_pwd  = doc["ota_pwd"].as<String>();
+  //prevent ota password is "null" if not exist key
+  if (doc.containsKey("ota_pwd")) {
+    ota_pwd  = doc["ota_pwd"].as<String>();
+  } else {
+    ota_pwd = "";
+  }
   return true;
 }
 
@@ -187,6 +192,8 @@ void save_advance(String tempUnit, String supportMode, String loginPassword) {
   // if support mode is empty, we use default all mode
   if (supportMode == '\0') supportMode = "all";
   doc["support_mode"]   = supportMode;
+  // if login password is empty, we use empty
+  if (loginPassword == '\0') loginPassword = "";
   doc["login_password"]   = loginPassword;
   File configFile = SPIFFS.open(advance_conf, "w");
   if (!configFile) {
@@ -334,8 +341,12 @@ bool load_advance() {
   //mode
   String supportMode = doc["support_mode"].as<String>();
   if (supportMode == "nht") supportHeatMode = false;
-  //login password
-  login_password = doc["login_password"].as<String>();
+  //prevent login password is "null" if not exist key
+  if (doc.containsKey("login_password")) {
+    login_password = doc["login_password"].as<String>();
+  } else {
+    login_password = "";
+  }
   return true;
 }
 
@@ -383,10 +394,15 @@ boolean init_wifi() {
 
 void handleNotFound() {
   if (captive) {
-    server.send(200, "text/html", html_init_setup);
+    String initSetupContent = FPSTR(html_init_setup);
+    server.send(200, "text/html", initSetupContent);
   }
   else {
-    String toSend = html_common_header + html_menu_root + html_common_footer;
+    String headerContent = FPSTR(html_common_header);
+    String menuRootPage =  FPSTR(html_menu_root);
+    menuRootPage.replace("_SHOW_LOGOUT_", (String)(login_password.length() > 0));
+    String footerContent = FPSTR(html_common_footer);
+    String toSend = headerContent + menuRootPage + footerContent;
     server.send(200, "text/html", toSend);
   }
 }
@@ -397,7 +413,10 @@ void handle_save_wifi() {
   if (server.hasArg("submit")) {
     save_wifi(server.arg("ssid"), server.arg("psk"), server.arg("hn"), server.arg("otapwd"));
   }
-  String toSend = html_common_header + html_init_save + html_common_footer;
+  String headerContent = FPSTR(html_common_header);
+  String initSavePage =  FPSTR(html_init_save);
+  String footerContent = FPSTR(html_common_footer);
+  String toSend = headerContent + initSavePage + footerContent;
   toSend.replace("_UNIT_NAME_", hostname);
   toSend.replace("_VERSION_", m2mqtt_version);
   server.send(200, "text/html", toSend);
@@ -407,7 +426,10 @@ void handle_save_wifi() {
 
 void handle_reboot() {
   Serial.println("Rebooting");
-  String toSend = html_common_header + html_init_reboot + html_common_footer;
+  String headerContent = FPSTR(html_common_header);
+  String initRebootPage =  FPSTR(html_init_reboot);
+  String footerContent = FPSTR(html_common_footer);
+  String toSend = headerContent + initRebootPage + footerContent;
   toSend.replace("_UNIT_NAME_", hostname);
   toSend.replace("_VERSION_", m2mqtt_version);
   server.send(200, "text/html", toSend);
@@ -418,7 +440,10 @@ void handle_reboot() {
 void handle_root() {
   checkLogin();
   if (server.hasArg("REBOOT")) {
-    String toSend = html_common_header + html_page_reboot + html_common_footer;
+    String headerContent = FPSTR(html_common_header);
+    String rebootPage =  FPSTR(html_page_reboot);
+    String footerContent = FPSTR(html_common_footer);
+    String toSend = headerContent + rebootPage + footerContent;
     toSend.replace("_UNIT_NAME_", hostname);
     toSend.replace("_VERSION_", m2mqtt_version);
     server.send(200, "text/html", toSend);
@@ -426,7 +451,11 @@ void handle_root() {
     ESP.reset();
   }
   else {
-    String toSend = html_common_header + html_menu_root + html_common_footer;
+    String headerContent = FPSTR(html_common_header);
+    String menuRootPage =  FPSTR(html_menu_root);
+    menuRootPage.replace("_SHOW_LOGOUT_", (String)(login_password.length() > 0));
+    String footerContent = FPSTR(html_common_footer);
+    String toSend = headerContent + menuRootPage + footerContent;
     toSend.replace("_UNIT_NAME_", hostname);
     toSend.replace("_VERSION_", m2mqtt_version);
     server.send(200, "text/html", toSend);
@@ -434,7 +463,10 @@ void handle_root() {
 }
 
 void handle_init_setup() {
-  String toSend = html_common_header + html_init_setup + html_common_footer;
+  String headerContent = FPSTR(html_common_header);
+  String initSetupPage =  FPSTR(html_init_setup);
+  String footerContent = FPSTR(html_common_footer);
+  String toSend = headerContent + initSetupPage + footerContent;
   toSend.replace("_UNIT_NAME_", hostname);
   toSend.replace("_VERSION_", m2mqtt_version);
   server.send(200, "text/html", toSend);
@@ -443,7 +475,10 @@ void handle_init_setup() {
 void handle_setup() {
   checkLogin();
   if (server.hasArg("RESET")) {
-    String toSend = html_common_header + html_page_reset + html_common_footer;
+    String headerContent = FPSTR(html_common_header);
+    String resetPage =  FPSTR(html_page_reset);
+    String footerContent = FPSTR(html_common_footer);
+    String toSend = headerContent + resetPage + footerContent;
     toSend.replace("_UNIT_NAME_", hostname);
     toSend.replace("_VERSION_", m2mqtt_version);
     server.send(200, "text/html", toSend);
@@ -452,7 +487,10 @@ void handle_setup() {
     ESP.reset();
   }
   else {
-    String toSend = html_common_header + html_menu_setup + html_common_footer;
+    String headerContent = FPSTR(html_common_header);
+    String menuSetupPage =  FPSTR(html_menu_setup);
+    String footerContent = FPSTR(html_common_footer);
+    String toSend = headerContent + menuSetupPage + footerContent;
     toSend.replace("_UNIT_NAME_", hostname);
     toSend.replace("_VERSION_", m2mqtt_version);
     server.send(200, "text/html", toSend);
@@ -466,7 +504,10 @@ void handle_others() {
 
   }
   else {
-    String toSend = html_common_header + html_page_others + html_common_footer;
+    String headerContent = FPSTR(html_common_header);
+    String othersPage =  FPSTR(html_page_others);
+    String footerContent = FPSTR(html_common_footer);
+    String toSend = headerContent + othersPage + footerContent;
     toSend.replace("_UNIT_NAME_", mqtt_fn);
     toSend.replace("_VERSION_", m2mqtt_version);
     toSend.replace("_HAA_TOPIC_", others_haa_topic);
@@ -491,7 +532,10 @@ void handle_mqtt() {
   checkLogin();
   if (server.hasArg("save")) {
     save_mqtt(server.arg("fn"), server.arg("mh"), server.arg("ml"), server.arg("mu"), server.arg("mp"), server.arg("mt"));
-    String toSend = html_common_header + html_page_save_reboot + html_common_footer;
+    String headerContent = FPSTR(html_common_header);
+    String saveRebootPage =  FPSTR(html_page_save_reboot);
+    String footerContent = FPSTR(html_common_footer);
+    String toSend = headerContent + saveRebootPage + footerContent;
     toSend.replace("_UNIT_NAME_", hostname);
     toSend.replace("_VERSION_", m2mqtt_version);
     server.send(200, "text/html", toSend);
@@ -499,7 +543,10 @@ void handle_mqtt() {
     ESP.reset();
   }
   else {
-    String toSend = html_common_header + html_page_mqtt + html_common_footer;
+    String headerContent = FPSTR(html_common_header);
+    String mqttPage =  FPSTR(html_page_mqtt);
+    String footerContent = FPSTR(html_common_footer);
+    String toSend = headerContent + mqttPage + footerContent;
     toSend.replace("_UNIT_NAME_", mqtt_fn);
     toSend.replace("_MQTT_HOST_", mqtt_server);
     toSend.replace("_MQTT_PORT_", String(mqtt_port));
@@ -515,7 +562,10 @@ void handle_advance() {
   checkLogin();
   if (server.hasArg("save")) {
     save_advance(server.arg("tu"), server.arg("md"), server.arg("lpw"));
-    String toSend = html_common_header + html_page_save_reboot + html_common_footer;
+    String headerContent = FPSTR(html_common_header);
+    String saveRebootPage =  FPSTR(html_page_save_reboot);
+    String footerContent = FPSTR(html_common_footer);
+    String toSend = headerContent + saveRebootPage + footerContent;
     toSend.replace("_UNIT_NAME_", hostname);
     toSend.replace("_VERSION_", m2mqtt_version);
     server.send(200, "text/html", toSend);
@@ -523,7 +573,10 @@ void handle_advance() {
     ESP.reset();
   }
   else {
-    String toSend = html_common_header + html_page_advance + html_common_footer;
+    String headerContent = FPSTR(html_common_header);
+    String advancePage =  FPSTR(html_page_advance);
+    String footerContent = FPSTR(html_common_footer);
+    String toSend = headerContent + advancePage + footerContent;
     toSend.replace("_UNIT_NAME_", mqtt_fn);
     toSend.replace("_VERSION_", m2mqtt_version);
     //temp
@@ -541,7 +594,10 @@ void handle_wifi() {
   checkLogin();
   if (server.hasArg("save")) {
     save_wifi(server.arg("ssid"), server.arg("psk"), server.arg("hn"), server.arg("otapwd"));
-    String toSend = html_common_header + html_page_save_reboot + html_common_footer;
+    String headerContent = FPSTR(html_common_header);
+    String rebootPage =  FPSTR(html_page_save_reboot);
+    String footerContent = FPSTR(html_common_footer);
+    String toSend = headerContent + rebootPage + footerContent;
     toSend.replace("_UNIT_NAME_", hostname);
     toSend.replace("_VERSION_", m2mqtt_version);
     server.send(200, "text/html", toSend);
@@ -549,7 +605,10 @@ void handle_wifi() {
     ESP.reset();
   }
   else {
-    String toSend = html_common_header + html_page_wifi + html_common_footer;
+    String headerContent = FPSTR(html_common_header);
+    String wifiPage =  FPSTR(html_page_wifi);
+    String footerContent = FPSTR(html_common_footer);
+    String toSend = headerContent + wifiPage + footerContent;
     toSend.replace("_UNIT_NAME_", hostname);
     toSend.replace("_SSID_", ap_ssid);
     toSend.replace("_PSK_", ap_pwd);
@@ -561,8 +620,10 @@ void handle_wifi() {
 }
 
 void handle_status() {
-  checkLogin();
-  String toSend = html_common_header + html_page_status + html_common_footer;
+  String headerContent = FPSTR(html_common_header);
+  String statusPage =  FPSTR(html_page_status);
+  String footerContent = FPSTR(html_common_footer);
+  String toSend = headerContent + statusPage + footerContent;
   if (server.hasArg("mrconn")) mqttConnect();
   toSend.replace("_UNIT_NAME_", hostname);
   toSend.replace("_VERSION_", m2mqtt_version);
@@ -583,9 +644,9 @@ void handle_control() {
   checkLogin();
   heatpumpSettings settings = hp.getSettings();
   settings = change_states(settings);
-  String controlPage =  html_page_control;
-  String headerContent = html_common_header;
-  String footerContent = html_common_footer;
+  String controlPage =  FPSTR(html_page_control);
+  String headerContent = FPSTR(html_common_header);
+  String footerContent = FPSTR(html_common_footer);
   //write_log("Enter HVAC control");
   headerContent.replace("_UNIT_NAME_", hostname);
   footerContent.replace("_VERSION_", m2mqtt_version);
@@ -1187,7 +1248,7 @@ bool is_authenticated() {
   return false;
 }
 
-void checkLogin(){
+void checkLogin() {
   if (!is_authenticated() and login_password.length() > 0) {
     server.sendHeader("Location", "/login");
     server.sendHeader("Cache-Control", "no-cache");
@@ -1223,12 +1284,14 @@ void handle_login() {
     msg = "Wrong username/password! try again.";
     //Log in Failed;
   }
-  String content = "<html><body><form action='/login' method='POST'>To log in, please user : admin and password<br>";
-  content += "User:<input type='text' name='USERNAME' placeholder='user name'><br>";
-  content += "Password:<input type='password' name='PASSWORD' placeholder='password'><br>";
-  content += "<input type='submit' name='SUBMIT' value='Submit'></form>" + msg + "<br>";
-  content += "You also can go <a href='/inline'>here</a></body></html>";
-  server.send(200, "text/html", content);
+  String headerContent = FPSTR(html_common_header);
+  String loginPage =  FPSTR(html_page_login);
+  String footerContent = FPSTR(html_common_footer);
+  String toSend = headerContent + loginPage + footerContent;
+  toSend.replace("_UNIT_NAME_", hostname);
+  toSend.replace("_VERSION_", m2mqtt_version);
+  toSend.replace("_LOGIN_MSG_", msg);
+  server.send(200, "text/html", toSend);
 }
 
 void loop() {
