Sometimes the settings for your displays will revert back to a different setting which makes using them difficult. Whether you are wanting them to display the same thing, or to extend the displays, you will need to do this:
Type Display Settings into the search bar on the bottom of your Windows desktop.
Click on it and the Settings app should launch.
It should look similar to this:
This computer is set up to extend the display, if you're wanting this but the mouse doesn't go to the other screen correctly, click on the correct display and click on Make this my main display. (If you're not sure which screen is which you can click on Identify and it will label the screens for you)
If you want them to show the same thing, you will click where it says Extend these displays and select Duplicate these displays.
If you like the change, you can click Keep changes or click Revert.
