Instructions
Log in to your Xbox 360 Gamertag and load the "Call of Duty: World at War" game disc in the disc tray.
Select "Options" from the Main Menu and scroll down to the "Button Layout" list item.
Select it and then choose from the "Default," "Tactical," "Lefty" and "NOM4D" button layout options.
Press the "Back" button to return to the previous menu with your newly modified button setup.
Begin or close the game. Your button layout modification will be saved to your Gamertag when you exit.