I also have this problem. However, I can hit f11 to enter full screen mode, then hit it again to exit and I get them back. The problem returns when I close and reopen firefox, but you can get your menus back this way.

I right click in an empty space in the menu bar, select customize toolbar . some how I did find a way, but still unhappy with changes made recently in Firefox .

What’s really annoying me, is that I have to deal with these unnecessary changes while working

i thank you for your prompt reply :)