From the settings tab navigate to 'Game Overlay'.Open Streamlabs Desktop and navigate to the settings tab in the top right corner.It will not work with a game in fullscreen mode. *Please note that you must run your game in borderless-windowed or windowed-fullscreen mode in order for this feature to work.
This guide will detail how to set up this feature and use it while streaming. This feature allows you to stream with one monitor while also keeping an eye on your chat and recent events. The new Streamlabs Desktop Game Overlay feature allows you to apply a toggle-able overlay of your recent events and chat on top of your game or activity.