Last Sunday we ran across a glitch over at the west campus in our student ministry venue.  The team had hooked up the Mac Book Pro to run ProPresenter for the morning on the projector.  Whenever we hooked up the projector, it would switch it to where the projector (external output from Mac Book Pro – DVI out) was the default desktop, and the built in computer LCD screen was the secondary monitor.  Usually a simple fix right?  Open up System Preferences, go to display, make sure mirror desktop is unchecked, hit the arrangement tab to switch them around…..no go!  We tried every reboot-disconnect-reconnect-display setting that we knew to try…still nothing.  On monday we discovered what the issue was.  It was a small update that Apple had released that a lot of people were not aware of.  If you’ve already discovered this on your own, that’s great.  If not, here’s the fix:

1.  Pull up the display preferences.
2.  Turn off Mirroring.
3.  Click the “Arrangement” tab.
4.  Click and drag the white bar from one window to the window you want to be the default/primary monitor.

Who knew?  You could move the small white bar.  Hope that is helpful.