UE4 games use nvidia gpu even tho monitor is plugged into motherboard

So today i plugged my monitor into my motherboard and to my surprise some games like fortnite and everspace and dauntless still use the nvidia gpu. I checked task manager and there was significant load on my gtx 1050ti and the fps was very high but some other games like pubg lite only use the integrated graphics of my i3 8100.

Is this normal? I didn’t know that this was possible.

mobo is Asus h310m-k btw this only works with UE4 games with pubg lite being an exception, i tried watch dogs, LOL and the crew and they only use the integrated graphics.

Any idea how I can get this to work with all games.