When a device is stolen then you need to change the password of the Sync account. That will cause all data on the Sync server to be wiped, but likely won't affect data stored on individual devices. When passwords were synced then this usually means that a master password had been used and a user would have to enter this master password to access the stored passwords and connect to Sync. ---- A detail like a website remembering you (log you in automatically) is stored in a cookie. You can use these steps to make a website recognize and remember you: *You can create a cookie "Allow" exception to keep specific cookies, especially in case of secure websites and when cookies expire when Firefox is closed. *Options/Preferences -> Privacy -> "Use custom settings for history" -> Cookies: Exceptions Let the cookies expire when Firefox is closed to make them session cookies instead of using "Clear history when Firefox closes" to clear the cookies. . *Firefox/Options/Preferences -> Privacy -> "Use custom settings for history" -> Cookies: Keep until: "I close Firefox" You can create a cookie "Allow" exception to keep specific cookies like for a website to remember you.