Apple TV 4K "use as separate display background"

[seabas]

So I am currently using my conference room to show presentations and when I use the option on my MacBook Pro to AirPlay the image I click on "use as separate display". So my issue is there is this blue screen as a background just showing onto the tv when before there was this beautiful background which Apple just gives you which is a desert landscape. All I am trying to figure out is how to change that background because it is very bright blue and annoying.

Thank you so much.

 

[priitv8]

You just use the Desktop & Screen Saver pane in System Preferences to set the wallpaper for secondary display.