If you clear cookies then websites won't remember you anymore and you need to login once again.

You will still have the passwords in the Profile Manager if you have saved them.

Tools > Options > Security: Passwords: "Saved Passwords" > "Show Passwords" Websites remembering you and automatically log you in is stored in a cookie.

Create a cookie Allow exception to keep such cookies, especially for secure websites and when cookies expire when Firefox is closed. Tools > Options > Privacy > Firefox will: "Use custom settings for history" > Cookies: Exceptions You can let cookies expire when you close Firefox. Then you keep cookies with an allow exception. If you clear cookies manually then all specified cookies are removed including cookies with an allow exception.

http://kb.mozillazine.org/Cookies https://support.mozilla.org/kb/Deleting+cookies

If you mean on Android, Firefox for Android lets you choose very specific categories of history to clear. See: Clear your browsing history and other personal data on Firefox for Android.

Clearing cookies wont make type in forms but you have to login coz u will be disconnected from the service.

I'll give that a try. Thanks for the info Roobin.