First, turn on the LG phone, and then press the Menu key. Go to Settings>More>Security, type your old security password, press Enter, select Change Lock Code, press Enter, type your new security password, and press Enter. Enter your new security password again to confirm it, and press Enter.
The LG phone hinders unauthorized users from gaining access to your personal phone through the phone lock feature. As long as you have knowledge of your current security password, you can make a new security password for your phone. LG makes a number of series of phones. To obtain more information concerning your phone's specific model, consult your user manual.