The Sims 2 Legacy

SO, when I first ran the game, it looked absolutely flawless and crispy AF, but I was playing in it's original resolution 800x600. AFTER, I fixed its settings to match my laptop's (MSI Kitana) resolution, which is 1920x1080, all of a sudden everything looks blurry and grainy and not at all like how it previously looked. Like, it looks like it runs on potatoes. So, initially tried switching back to the original resolution (800x600), it did absolutely NOTHING! 

ALSO my UI is extremely TINY after switching it to my laptops resolution :(

Please leave any suggestions to any fixes you may have!!