Extending and duplicating displays:
Your computer may not automatically select the correct type of display settings you want when you try to connect a second screen or an external display like a projector.
Please make sure the second display device is already connected and powered on and then follow these steps;
1) click on the start button and navigate to the control panel
1a) If you are using windows 10 you can navigate to the control panel by right clicking on the windows icon and selecting control panel.
2) click on the “display” link
3) On the left hand side of the display window select the “change display settings” link
4) use the drop down menu to select either “duplicate displays” or “extend displays” depending on which you need.