Instructions
Scroll to your PlayStation Network ID, and press "X." Enter your password. Press "X" to sign in.
Scroll to the PlayStation Network menu. Select "Account Management." Choose "Account Management" again on the next screen.
Select "Edit Online Profile." Your current avatar appears at the top of the screen. Scroll right and left to see the available avatars. Highlight the desired avatar, and press "X."
Leave the information on the next page unchanged. Select "Continue" twice to switch to the new avatar.