diff --git a/signature-extension/api.js b/signature-extension/api.js
index 65c6c26..789d7f1 100644
--- a/signature-extension/api.js
+++ b/signature-extension/api.js
@@ -1,5 +1,5 @@
-const OAUTH_CLIENT = "";
-const OAUTH_SECRET = "";
+const OAUTH_CLIENT = "<CLIENT_ID>";
+const OAUTH_SECRET = "<CLIENT_SECRET>";
 
 const ERROR = "Authorization error";
 const REDIRECT_SUBDOMAIN = browser.identity.getRedirectURL().substring(8);
diff --git a/signature-extension/background.js b/signature-extension/background.js
index 8777eb8..14ac54c 100644
--- a/signature-extension/background.js
+++ b/signature-extension/background.js
@@ -60,7 +60,7 @@ let defaultPreferences = {
   oauthSecret: "",
   failedCount: 0,
   changelogShown: 0,
-  useOwnCredentials: true,
+  useOwnCredentials: false,
 };
 
 function changelog() {
diff --git a/signature-extension/changelog.html b/signature-extension/changelog.html
index bff489e..204e244 100644
--- a/signature-extension/changelog.html
+++ b/signature-extension/changelog.html
@@ -17,6 +17,11 @@ <h1>Welcome in the new version of Signature sync for Gmail!</h1>
 
     <h2>Version 2.0.0</h2>
     <ul>
+      <li>
+        <b>Important change.</b> The add-on (version from Thunderbid add-on portal) contains now
+        default OAuth credentials, but it still during certification and can handle just limited
+        number of users.
+      </li>
       <li>
         <b>Breaking change!</b> Use "desktop app" oauth client type. Your OAuth credentials requires
         update. Please follow
diff --git a/signature-extension/options.html b/signature-extension/options.html
index fa48056..41260e1 100644
--- a/signature-extension/options.html
+++ b/signature-extension/options.html
@@ -34,24 +34,19 @@ <h2>Accounts to sync</h2>
   <h2>Google OAuth ClientID</h2>
 
   <p>
-    As for now you need to create your own OAuth application in Google to make the extension
-    working. Registring OAuth application allows you to use Google API what is necessary to sync
-    your signatures. This is free and you can find instruction on the
+    The add-on is currently still under Google certification and can handle just limited number of
+    users. At any time you can create your own OAuth application in Google. This allows you to work
+    independently of the add-on defaults credentials. This is free and you can find instruction on
+    the
     <a href="https://github.com/kam193/thbrd-signature/wiki/Registering-own-OAuth-app-in-Google">
       extension wiki</a
     >. Then put the ID and secret you get in the field below.
   </p>
   <p>
-    <span class="browser-style nobottom"
-      ><input type="checkbox" id="oauth-use-own" checked disabled /></span
-    ><span class="text">Use own OAuth credentials (required for now)</span>
+    <span class="browser-style nobottom"><input type="checkbox" id="oauth-use-own" checked /></span
+    ><span class="text">Use own OAuth credentials</span>
   </p>
   <div id="oauth-form">
-    <p class="notice">
-      The extension version with pre-defined OAuth client is ongoing, but registring publicly
-      avialiable OAuth application in Google needs additional time and a few limitations that not so
-      obvious for just a simple Thunderbird extension.
-    </p>
     <p>
       <input type="text" class="wide" id="oauthid" placeholder="Your OAuth Client ID" />
       <input type="text" class="wide" id="oauthsecret" placeholder="Your OAuth secret" />