Why can't I sync my passwords?
If the Passwords checkbox is disabled in the Sync preferences window, it's because you have set a master password.
Firefox Sync will not synchronize your passwords if a master password is set. If you would like to continue synchronizing your passwords, try removing your master password before synchronizing.
This issue will be resolved in Firefox 34.
Dela artikeln: http://mzl.la/1ApHpPs