I was a little freaked out when my custom setting gear icon disappeared from my screen.
What had happened was yesterday popup descriptions of every item on the menu started appearing and I wanted to get rid of them, so I went into the setup menu (wrench icon) and turned off the display thinking that would solve the problem, but it didn't.
What I had to do was hit the INFO button, which is responsible for changing a lot about what is displayed on the screen.