My computer froze, so i restarted it with the power button. When it loaded back up, all three screens were mirroring each other, and their resolutions had been changed. I fixed screens 1 and 2, but screen 3 doesn't have any resolution options above 1024x768, even though it should be 1600x900 like screen 1. Screen 3 is plugged in through the display port, if that matters. I'm on ubuntu mate 20.04.1
Hi 
I would unplug everything and plug each one after the other with configuring each one after it is plugged.