I was fooling around with the toolbar options, trying (unsuccessfully!) to return to the toolbar layout I had before Firefox was automatically upgraded (without my permission!). I was trying to move the tabs bar down below the other toolbars. Suddenly it disappeared. Various web-suggested fixes involved going into Preferences or Options and doing things. I can't find anything called Preferences, and the option suggested for tabs (show tab bar) in Options doesn't exist in my options. I am very unhappy, not just because I can't find the tab bar, but because the new version messed up how I had my toolbars organized, and there seems to be no option for fixing it.