How to configure monitor displays in windows 10
Open display settings. There are two ways to do this
Right-click desktop and select Display settings
Open the start menu and click the settings icon
Click system settings
Identify your monitors. The identify button will show the numbers corresponding to each of your monitors on your screen in large letters. Make sure the monitors are in the correct order. You can drag and drop the monitor icons on your screen so they are in the correct order. (hint: Your monitors may not be in order like mine. Just make sure the icons match the order you see when you click identify.)
Change which monitor is your main display. Scroll down near the bottom of this page. There is a checkbox option to set the display selected to the main monitor. Select the display you want as the main, and click this checkbox.
Extend your desktop. If your desktop is duplicating on two monitors, and you would like to change it so your desktop extends to the other screen instead, change this setting. Scroll down the screen until you see a drop down list. Yours may say "duplicate desktop on 1 and 2" or similar. Change this to "extend desktop to this display."
Make sure windows is detecting all monitors. If you have more monitors than windows is detecting, follow these steps.
Click the detect button
Extend all desktops. Click on each display icon, and set all to "extend to this display". Many times, the missing monitor will become available.
Check that display cables are plugged in all the way