The ability to add colored backgrounds to slides/presentations is available inside of the Editor window. There is a setting that can toggle whether these background colors send to your output or not. To confirm this setting is set the way you’d like it to be for the best use in your environment, you would go to ProPresenter Preferences.
In the Screens tab, you can toggle the “Ignore Background Colors” option off or on by checking the box. If this is enabled, the standard transparent background would appear behind your presentation slides instead of the color you selected.
This feature was traditionally used in previous versions of ProPresenter as users would change the background color to make their slide thumbnails easier to see when using the Alpha Keyer Module. This is less of a need due to changes in the View modes. You can read more about viewing your slide thumbnails in our article here.