Find "Change unlock pattern"
Press Applications.
Press Settings.
Press Location and security.
Press Change unlock pattern.
Change phone lock code
Press and drag a point to connect the points in the existing phone lock code.
Press and drag a point to connect at least four points to select a new phone lock code.
Press Continue.
Repeat the selected phone lock code to confirm.
Repeat the selected phone lock code to confirm.
Press Confirm.
Exit
Press the Home key to return to standby mode.