1. Turn off your PSP by holding the power button for 4 seconds.
2. Turn on your PSP and hold the 'R' (Right Trigger) button to enter recovery mode.
3. Select the 'Registry Hacks' Menu and press 'X'
4. Select 'Button Assign' option and press 'X', this will switch 'O' and 'X' buttons.
5. Select the 'Back' option and press 'X' to go back to the main menu.
6. Select the 'Exit' option and press 'X' to go back to the XMB.