Find "Change security code"
Press the Navigation key.
Scroll to Settings and press the Navigation key.
Scroll to Security and press the Navigation key.
Scroll to Access codes and press the Navigation key.
Scroll to Change security code and press the Navigation key.
Change phone lock code
Press Yes.
Key in the current phone lock code (default is 12345) and press the Navigation key.
Key in a new phone lock code and press the Navigation key.
Key in the new phone lock code again and press the Navigation key.
Exit
Press Disconnect to return to standby mode.