obs not recording right

I've been trying to use OBS for a couple of months now and I just can't get it to work. Even on simple games like terraira, after about 20 minutes I get the overload message and the video turns out really laggy. Ive tried to many different things and i just cant get it to work at 1080p 60fps...

I can't make make videos longer than a few minutes without OBS breaking the video up into smaller videos. Could it be a setting? I need help! I was making videos no problem and this started a few weeks ago and I can't make it stop. I included an image of my save folder. All of those videos...