Changing Emulators Before a Game Boots

I know this is possible because my friends pi asks which emulator to use before loading a game but mine does not. Basically the emulator used for my N64 games is choppy and I want to try others. I have read that you need to use a keyboard and press X during the black screen right before the game loads but this does nothing for me. The game just keeps loading. Does anyone know what I am doing wrong? Should I just restore the pi back to its original settings by burning a new image? Thanks.