I dont want to speak as an absolute authority, simon is very skilled (clearly) and has built this forum from the ground up so i will defer to him in the final analysis. That said, i susspect its a setting in firefix. I tried both from my laptop and my iphone and have stayed signed in with no issues but im using chrome not firefox. Sorry i cant be more help in that speific situation shirley.
blondie, im NOT a fan of IE. Switching to chrome will not hurt you or anything ypu have saved specific to IE. You will not he uninstalling IE when you install chrome. In other words, go ahead and instal chrome and try it. If you dont like it then you just resume using IE with no negative consequences. In my professional life i have migrated many people from IE to chrome and they all like the switch. Like anything else, there are a few differances to adjust to but its very inutative and much faster than IE.