Kathy,
I don't recall asking how you created your presentation - you noted in your
first post that you are using PPT Plex.
I do see that I suggested that you contact Office Labs directly. I urge you
again to do so. PPT Plex is something that they are working to refine, and
they dearly value customer input.
Also, I tested the situation you described by changing the font on the
canvas slide, the section divider slides, and the slides after the section
dividers. I was able to do so without any problem - I changed the font from
default Arial to Algerian, and they maintained the Algerian formatting when I
viewed the slide show. I was able to zoom and pan across the canvas, and all
the text maintained the Algerian font.
Note: I was using the "Breakdown" canvas.
What font are you trying to change the text to? That might make a difference
as well. Check out Steve Rindsberg's article:
Troubleshoot font problems
http://www.pptfaq.com/FAQ00402.htm
I have noted some oddities in PPT Plex depending on the number of times that
you have run the slideshow. Right now, I've had the best luck with making all
formatting changes before I view a presentation in slideshow. It's a
workaround, but at least you'll get a font other than Arial!