I'm giving my old Galaxy S7 to a friend, I've got her a prepaid SIM and put it into the S7 (my own SIM has gone into a new S22). I've managed to set up the S7 to sync with her data via DAVx5, Thunderbird was easy to set up thanks to the QR-Code export, and various other things worked as expected. BUT she uses firefox sync, and so do I. I deinstalled firefox on the S7, and reinstalled it, and changed to her sync account - but all my own personal data (bookmarks, chronology etc) are still there. That's not only really annoying, but also a breach of my private sphere. Google KI tells me to give her sync account a new password, before doing that decoupling from sync on all used devices; we have five, so that would be a real pain. The only other option I see is a factory reset and then repeat all the work setting up the S7. So what I'm asking for is an option when firefox is deinstalled, or as an extra option in the settings, to delete all stored personal data.