Display issues

For some reason when I maximize any window it will not go full screen, this issue just popped up this morning after I moved my taskbar to the top of my screen (decided I didn't like and moved back to the bottom) but, now I can't use the space where the task bar would be (if it were at the top) I have attached a picture of what firefox looks like maximized. Does anyone know how to fix this?

Also, I have had lots of display issues and can't seem to fix them, one is that my computer seems to think it has three default monitors in the device manager (picture also attached), if I delete one it will eventually come back. I think this problem may be linked to my resolution changing automatically when I close the lid of my laptop or may be the cause. If anyone can help with either issue I'd greatly appreciate it!

EDIT: Well I figured out the first problem, it was due to OD, I checked reserve edge of screen without knowing. I still do not know how to fix the other issues though...

 

I have 2 default monitors listed in device manager. It's always been that way for me.