Some years ago I had to replace my PC and thought - Wonderful - just use sync to bring back all my tabs etc into the new PC... The long and the short of it (in the past), was that Firefox decided that the new PC was the one to be synchronising source, and promptly removed all the apps/tabs etc. so sync was in line with the new PC - erasing all the app data. I understand there is no 'Master' sync account. The question is, how can I stop Firefox initially migrating the Firefox app data in the wrong direction? I know that the app/tab data is currently still correct as my laptop still has all my apps etc. Is there some way to stop Firefox thinking the latest clean browser on the new PC has the correct (None) apps etc? Has the laptop to be logged-in and currently on-line before starting the new PC with Firefox? Is there a process to follow with a new 'un-synced' PC? Sorry if I'm making things sound difficult, but don't want to loose everything which is currently correct and still these within sync data. It's maybe something that can't happen in these later versions of Firefox, but I want to be sure before logging in my new 'Blank' PC.