How to manually trigger password lock

[AC Question]

I have a password based lock, which works fine. However, if I manually lock my phone by using power key, it only requires a swipe to unlock, not a password.
I need to be able to lock my phone to that the next time someone uses it, they must enter the password. I have lil kids, and they run away with my phone and use it even when they don't have my password, because I cannot lock the phone with password manually.