I recently uploaded macOS Big Sur onto my MacBook Air. At that point, my Firefox turned into a question mark on the tool bar and I have to sign in to Firefox Sync whenever I click on the question mark (which then becomes the Firefox symbol). Meanwhile, I clicked a link in an email, and this led to a second Firefox showing up in my toolbar. Both are Firefox browser 83.0, 64-bit, but the second one doesn't require signing in. However, the first one (the Sync) did retain my bookmarks. What is going on? And what do I do to just have one version of Firefox, preferably one that retains my bookmarks? Thanks for any advice!