Dual monitor default background image

[anyese]

I use powerpoint for my church. As soon as I connect my MAC to the facility's projector there is an image that pops up. Where does it come from? Can I change it? Once I start the slideshow the background is whatever I selected when I set up the show but the wallpaper that seems to be some kind of default is illusive. Of course, when I'm at home I have only one screen so I can't figure it out. Help????

 

[DeltaMac]

When you have the projector connected, open your System Preferences, then the Desktop & Screensaver pref pane.
You will see that you get a pref pane on both your Mac, and the projector screen.
And, you can change the background on the projector screen to something else (independent of the background on your Mac). I created a second background that is pure black, with the name of my church in small faint letters on that screen. That way, it's relatively unobstrusive, but I can tell at a glance that the projector is working, and that the computer is providing the image that I want, ready for the powerpoint/whatever.