This article covers how to assign an Overlay app to dedicated screens.
Prerequisites:
Overlay App activated. Learn here how: Overlay App - Activate and use
Adding the Overlay App to selected display(s)
Go to Tools / Overlay Apps
Click eitherSet Overlay App active
Once you have selected your Displays, choose your Overlay App from the drop-down menu.
Click SET OVERLAY APP TO SELECTED _ _ DISPLAYS to activate your Overlay App.
Your selected Display "boxes" will look like this after selecting and setting the Overlay App to your Displays.The Overlay will be active and visible on your screens under 10 minutes.