So for years I was using a 24" screen. I finally upgrading to a 27" screen and now notice all my games from here, well old ones load up in a small window in the middle of my screen. With no way that I can see to change it within the game. Is there something within the files I can change so I don't get this problem?

You likely have 1:1 pixel ratio enabled on your monitor. Try looking for it in the monitor controls.

To be honest, though, this might be your best chance at playing then in a non-ugly, super-stretched way.

Oh I see, it's normally just sitting in full. But when I loaded up a game, like age of empires 2. It changed to 1:1. I didn't even know I could change all that in the monitor settings haha. But seems I could mostly fix it. Couldn't go full screen. But went close enough that it's heaps more playable.

Thanks so much.

Glad to help! Enjoy your games!