Can some body help me in the house,we just brought projector in our church and will use it to projet sermon,song.but hw can we change to another presentation without showing the desktop background when using powerpoint.

there's software on the market that is targeted towards church use so it prolly would deal with that and other problems you might face. . .cant really get a hang of what your problem is tho. . .its seems to hv somefink to do wiv minimising abi?

why not prepare the slide to contain all the presentation for that day

Why not create all your slides in a single ppoint file and run ppoint in full screen mode? Then use the cursor keys to move from slide to slide?

I realize that some of the projectors have a free button, that allows you to make use of your switch. why not read
the documentation of your projector properly first, and then check online too otherwise
you may use the alternative suggested by the last poster.