Help with Firefox if possible please.

[Scooby73466]

Windows 8.1 64 bit desktop with fully updated version of Firefox as default browser here and have just encountered an annoying problem insofar as Firefox had a giddy turn and I have had to reset a few user options. But I have one thing that I can't get it to work how it used to. It's all about bookmarks and where they appear. Prior to the problem, whenever I clicked on the Other Bookmarks tab, the list always opened in the LH margin of the screen. I can still get it to do that if I press cntrl+B. But if I just press the tab now it opens in the RH margin which is a bit of a nuisance because that is also where the list of the "Show More Bookmarks" appears whenever I click that tab.

Can anyone help me please by telling me how I get the Other Bookmarks list to open in the left hand margin when I just click the tab as opposed to having to press cntrl+B ? Thanks in advance for any help of advice.