How do you Mirror Display in Impress

Ok, we decided we wanted to try LibreOffice and move from Power Point at our small church. We project songs for our song service to a large screen in the sanctuary. Our set up consists of two computers. 1. is a Mac Mini using Keynote for sermons. 2. is a HP PC for the songs. We run HDMI out of both computers to a switch to a projector that uses VGA. The Mac works no problems. When you switch to or from the PC it pitches a fit, tongue in cheek there, and goes blank on what is displaying. When running PowerPoint we had to mirror the display so automatic would step in and try to match the resolution of the projector by dropping out and coming back. I tried to do this with Impress last night and needless to say it wasn’t too impressive. I had to switch back to PowerPoint quickly but then we get the message powerpoint needs to repair itself.
Any ideas 1. how to get to the Presentation Console to see if there is a mirror display or is this something that was left out. I am all for Open Source software but feel left out on our own at times. Any help appreciated - macmikeal (at) me (dot) com.