There not changed to an FF icon. But, they can be changed from an FF icon. If you download something using FF or GC often it will come with an FF or GC icon. These can usually be changed by opening the menu clicking properties at the bottom of the menu. Then clicking change icon. Then scroll through the icons and plck one you like. Every once in a while you'll get one that can't be changed, from a FF or GC icon
I don't know why GC and FF use their own icons. Instead of icons that better depict
the program that was downloaded. Ray