"I don’t know why, but the res looks like shit when I play it but when others do, it looks good."
1. Make sure antialiasing is off, the lower the res the blurryer, so turn off that
2. You may have a 1920x1200 monitor (16:10)?
3. If you have 2560x1440 monitor use 1 res above what it would be on 1920x1080, so say on 1080p default stretched is 1440x1080, where as on 1440p it would be 1920x1440