The right volume wheel on the headset controls the game/chat balance when the headset is in Gaming Control Mode.  To use the game/chat balance control rotate the wheel clockwise to increase the game volume and rotate it counter-clockwise to increase the chat volume.  When you reach the end of the adjustment in either direction a beep sound will be heard in the headset meaning that the balance is either 100% game or 100% chat.  If you rotate the wheel to the middle setting a double beep will be heard and that will indicate that the game and chat volume levels are the same.

Once you have found the desired game/chat balance, use the left volume wheel to control the overall volume of the headset.