With the "Open previous windows and tabs" preference checked on a PC (don't know if Mac or other has this issue), if you had multiple windows open, closing all of them at once via "Close all windows" in the Firefox app's Tasks menu on the taskbar (with multiple windows open, right click the Firefox app on the taskbar to open the Tasks menu, then click "Close all windows"; if only one window open, it'll say something singular instead of plural), it used to be so that when you try to reopen Firefox, all your multiple previous windows would reopen. Instead, it now only reopens one of them, I think maybe the last window you were looking at. Now you could try to reopen the other windows via the History -> Recently closed windows, but that's assuming that the other windows are saved onto there, because it seems that there are times when they are no longer saved there. I'm not sure this is for sure the reason why it's no longer in History anymore, but my place has had some electrical work being done by the city outside, so twice there have been notices given that the power would be shut off within a short period, meaning twice my PC was shut off within that short period. My guess is that after it shut off the first time, I had that short period of time to reopen the other closed Firefox windows because it was indeed saved in History, but I didn't notice that Firefox didn't reload ALL of the windows - only one. So when the power shut off a second time, that history was lost. This is just a guess - maybe Firefox auto deletes it after some time, idk. But mine are no longer there, so fml I guess. I also tried sessionstore-backup, but the earliest one was within the last 2 weeks and the other windows still were not in the History. Is there some second Preference checkbox option that needs to be checked, or can y'all change it back to what it was before?