The phone lock code protects the contents of your mobile phone from unauthorised use. If use of phone lock code is activated, it needs to be keyed in when you turn on your mobile phone or when it has been in standby mode. Remeber, first you need to activate use of phone lock code.
Find "Change Passcode"
Press Passcode Lock.
Press Change Passcode.
Change phone lock code
Key in your current phone lock code.
Key in a new phone lock code.
Key in the new phone lock code again.
Return to the Home screen
Press the Home key to end the session and return to the Home screen.