‘Firefox Saved Logins’ is not a standard cleaning option in Custom Clean.
It is one of the user defined extra cleaning options from the Winapp2 add-on which is not written by CCleaner themselves but is a user created and user maintained add-on.
Any cleaning option in Custom Clean that has an asterisk (*) next to it is from Winapp2 and not from the Standard CCleaner.
It is genarally assumed that if you are using Winapp2 then you are an advanced user.
I suggest that you repost in the Winapp2 thread where you will get more help with the Winapp2 extra cleaning options.
Heres a link:
When you repost there please clarify -
Have you actually lost the saved passwords? Or are you just being logged out if sites and have to log in again?
(Whether you remain loged into a website after closing/reopening Firefox is saved in either a cookie or saved in your Firefox ‘Session)’.
If you go to ‘Passwords’ on the Firefox Settings menu are they still there?