Is there a way to completely lock my phone?

[Android Central Question]

My boyfriend keeps going into my phone while I'm sleeping and silencing it. Apparently you can do that without a password or lock code or anything. Is there a way to completely lock down my phone so it's unusable except to me?

 

[Rukbat]

A password that no one can guess. If he knows you well, most of the passwords you'll use are things he can figure out. The only other way is biometrics - retina scan or fingerprint. (Facial recognition is too easy to fake.)

 

[B. Diddy]

Welcome to Android Central! Which phone do you have? On my Pixel 2 XL, if it's on the lockscreen, the volume buttons can only control Media Volume, nor Alarm Volume. Is your BF somehow turning down the Alarm Volume? Or can you just ask him not to do that?