Resolution:  

1. Right click a blank space on your desktop.
    
2. Click on "Display settings"
    
3. There should be some boxes on your screen with numbers in them, click the drop down bar on the right, and set it to your preferred option. Typically, either extend (to use multiple monitors separately) or duplicate (to have all monitors show the same thing)
    
4. Select "Keep changes" if it looks right, or "Revert" if it does not.