Opera button top left corner is where you'll find settings located,see no reason not to reset to defaults then reset the homepage again.Opera,firefox & chrome all use the same engine.There is two 64bit firefox versions the other being waterfox
mozbackup -portable app to make backups of your mozilla firefox/waterfox settings,history,addons etc,etc
http://sourceforge.net/projects/mozbackup/
edit:however now you have ff you'll most probably not go back hehe
useful addons you may like to try
adblockedge -blocks ads
flashcontrol -stops auto play of flash content by placing a play button dead center in flash,hit it if you want content to play
all-in-one sidebar -handy collapsible sidebar for your fav's,addons,downloads & history
NoSquint -auto sets pages for easier reading by increasing fonts size
ghostery -blocks tracking cookies
speed dial -similar to opera
addons here can be got here
https://addons.mozilla.org/en-US/firefox/