Dark square shadows under Sims

Hi I know it's been a while. I eventually found the time to play again today, but the shadows were so extremely glitchy and my sims disappeared and reappeared a few times, so I went into my graphics setting and starting changing things to try and fix it. I looked at retina display and read that it can slow some computers down, so I tried turning it off and it froze into a weird screen (there should be a screenshot) I eventually had to force quit the game. I'm just tired at this point, there are just waay too many glitches and bugs that I can barely enjoy my game, and I don't feel like playing anymore. But thank you for your help.