How can I trust him...

How can I trust my boyfriend again... every time I go on his phone randomly I’ll see a half naked girls and this is all the time he says he’s not looking at them and blah blah but I see it all the time. He’ll stare at woman in public and it pisses me off because why are you starring. We’ve talked about it and he says he’s not starring but anyways can I have some tips on how to trust him again. No I don’t need to hear “ you shouldn’t be with if you can’t trust him” and all the other stuff . Just need some tips on how to build trust again. Pls and thank u