A family of Microsoft presentation graphics products that offer tools for creating presentations and adding graphic effects like multimedia objects and special effects with text.
UPDATE Sept 6, 2018
Sadly this doesn't seem to work on some of my files which have been passed back and forth between Keynote and PowerPoint with many changes to the slide and Notes master. I'm now going to try the ppt alchemy macro (in reply further on in this thread). Some notes pages updated beautifully to the revised template following my procedure below, but because many of the slides have been mashed up from old presentations, I fear my simplistic solution won't work for the majority of my slides. I wish I could figure out a way to paste content into a pristine new file which would eliminate any ties to past templates or themes and apply the new ones.
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I may have finally found the solution to the notes master problem in PowerPoint 2016 for my situation.
I created a clean new file from my clean new template (with notes and slide masters the way I want them). I have gotten to the point that we're now all using the same slide template (that's been a chore). It took awhile so that when I follow this method, there aren't a lot of problems to deal with in slide formatting. If you never create your own slide masters you may not have a problem.
That said, I just experimented by creating my empty file from a potx template (New from Template command). The template has both slide masters (and theme which includes fonts and colors) and a notes master with slide and note placeholders, font and font size specified.
Then, I opened the deck with the slides I wanted to fix and copied them. DO NOT use Insert Slides From Another Presentation. That DIDN'T work.
In the new file, I paste the slides using DESTINATION theme (click on the paste icon - it's an option). This is a critical step. If you let SOURCE theme stay, all bets are off.
I was actually shocked this worked. I have only spent about 10 minutes testing with a prez of 87 slides, but it seems to work. My new notes master has a smaller slide, I moved and increased the size of the notes box, changed the font, font size, and cross my fingers, it seems to be working. My test changed a lot so I could quickly see if the changes were applied.
Considering how often I have come looking for a solution to this forever, I am really excited that I may have figured a way around all the notes formatting issues that have plagued our repository of 3,000 slides!!!
Woo hoo!
Barb