Firstly, Firefox Sync is entirely optional. It has nothing to do with make you part of a community. It's intended for people who have multiple computers and simply want their bookmarks and other data to be the same between all of their devices. If that's not something that you need, you can use Firefox without Firefox Sync. As for your passwords missing, you can check either the [[Fix passwords disappearing due to AVG security software]] page (even if you don't use AVG) of the [[Recover lost or missing Bookmarks]] page to see if either of those help you. Hope this helps.