Because my Mac was a bit slow, I decided to close several apps and reboot. Normally, Firefox opens at restart with all my previous tabs intact. The Firefox tool bar opened but the browser page did not. It appeared for a nano second and was gone. I opened Safari and downloaded Firefox. After upgrading to Firefox 89.0 and spending hours setting up tabs, menu bar, extensions, etc. I closed and restarted to test to see if I was going to have the same problem as before. All my settings were gone and I had to sign in and restart from scratch. I vaguely remember that I should be able to open Firefox without signing in. Thanking you for your help in advance. Mac 11.4 Big Sur