Find "change password"
Press arrow right to access the main menu.
Press Settings.
Press lock+wallpaper.
Press change password.
Change phone lock code
Press the field below Current password and key in the current phone lock code.
Press the field below New password and key in a new phone lock code.
Press the field below Confirm password and key in the new phone lock code.
Press done.
Exit
Press the Home key to return to standby mode.