I'm fairly new to Ubuntu, so I'm going to need a little bit of hand holding. I've searched this problem and have tried a few things.
First, some information. I have a dual-booted computer with Windows 10 and Ubuntu 16.04. I have two moniters, one that is connected with a HDMI cable and one that is connected with VGA. My graphics card is a Radeon R9 290/390.
On Windows 10 I have no problems with this, but when I boot up in Ubuntu, the moniters are stuck in mirrored mode, showing me the same thing twice. When I try to change this it doesn't seem to acknowledge the moniters as separate.
I have tried uplugging each moniter and individually both are detected, as I can use either one. But when I plug in the second one, I don't see a new moniter showing up as an option.
I have installed ARandR and it has not helped, it still only detects the one. I have searched this problem and have found others with the same problem, but have yet to find a solution that has worked.