Appearance of Firefox

I posted this a few days ago but can't find it to see if someone replied. Hello I've inadvertently changed my Firefox settings while I was using the new background feature. The pages are now all white and text boxes on programs highlighted. Many aspects are highlighted and I can't see the cursor at times. Would you point me in the direction to get support please? thank you, Susan I cannot click into the box below: ' Email me when someone answers the thread'