When I right-click in Firefox my menus are grey with a slightly darker grey for the font which is difficult to read. Is there a way to manually edit the background colors of these menus?
You can change EVERYTHING in Firefox - it is open source software after all, and you can make it dance on its head, if you are so inclined. But if you don't feel like poking through code, just change your theme. Find something brighter - there are plenty to choose from.