I’m on Windows 10 with an Asus notebook connected to the UD-3900. I have two external monitors, connected to the UD-3900 via a DVI cable and a VGA-to-HDMI adapter. I am trying to get the main display on the notebook duplicated to one of the monitors so I can close the laptop. When I choose this option, the monitors flash and I can see the “Keep these display settings?” dialog box on on of the monitors, but I cannot select “Keep changes.” “Revert” is the only thing I can click on. Then it goes back to displaying on all three screens.
What’s ironic is that I can get this set up using my Windows 7 laptop that’s ancient compared to the ASUS!