Instructions
Access the "Options" menu within the game. You can do so either from the main menu when you start the game, or at any point during your gameplay by pushing the "Start" button (looks like a "Play" button on your Xbox 360 controller).
Select "Controls" from the "Options" menu. Through this menu, you can also change audio and video settings, control new downloadable content and change gameplay preferences.
Change the buttons to represent the actions that you want them to complete. You can change all of the main buttons, as well as the bumpers, triggers and thumb-stick actions.