In system preferences, under Security and Privacy, the "Require Password" box is not checked. Interestingly, even when I have entered my password and the lock icon is open, I cannot check this box - I click on it, and the checkmark briefly appears and then goes away.
Despite the box not being checked, my computer almost always makes me type in a password when I open it or after it goes into the screen saver.
Occasionally, it does unlock automatically, but when it does so, I cannot click or interact with any windows, and I have to shut and open my screen again and type the password in order to actually use my computer.
I am using a MacBook Air running macOS High Sierra.