Fiancee delating his browser history?

Hi ladies. I want to ask for some input because I don't really know what to think of all this.

So little background, right now my fiancee is working nightshifts, so even when he is off for a few days, he will sleep during the day and be up all night pretty much. I usually plays games on his pc, as me and baby are asleep etc.

So yesterday he was taking a bath and just before he got one, we were checking laptop specifications as I'm buying a new one, we were doing this together on his account on the pc(I know the password etc he knows mine), so when he was taking the bath, I wanted to go back to one i looked at because I couldn't find it after and he told me to look on the history to find it again. So I did. Out of curiosity I scrolled down a little, and to my surprise there is massive gaps in times that he was on the pc in the history. So say if he was on his pc all night long, there is browser history say up until 2am, and then nothing until 6am, apart from a few Google searches. I thought at first maybe he was playing a game so wasn't on the browser, but then I remembered that on Friday night I woke up about 3 times and each time he was on Google and websites. But in the history there is absolutely nothing for Friday after 3pm, which there should be because I seen him on different websites. Later that day I wanted to use a printer which is only connected to his account, so I went to log in and the password has been changed. I mean, it was my daughters date of birth, and now it's changed. I wouldn't log into it ever without telling him, but I wonder why he changed it not like he could forget that password.

Should I talk to him or would you just drop it and move on? Basically he has a history about 3 years ago of having a second Snapchat and talking to girls on there, and going to sites like chatroullete to talk to girls etc, I thought we moved past that but now Im not so sure.