Good morning Gary, Firstly, may I thank you for your patience. I finally managed to create the movie to my satisfaction in iMovie. Previously saving the slideshow from Keynote to HTML, Powerpoint or Movie - it could not be opened on a Windows computer. (3 people tried to do this for me).
However, I now have MEGGA problems after saving it to mp4. It did save to mp4 but was oversized, with the top and bottom missing and the movie full screen. I tried all the usual, zoom etc. No good. I was alerted that my storage was surprisingly very low, and so tried to delete large files or save to ex.d. (A little success). But the big problem is the Mac screen resolution which is huge. I have tried to restore defaults: Apple logo-sys.prefs.-display. Tried all options, including scaled on or off. Zoom works a little resulting in only part of an app or whatever I open, eg. BBC News, showing. My movie opened in QuickTime, which I have also checked and left set to default.
Have you any advice? Or do I need to contact Apple, or the local engineer? I am at a loss, having tried everything I know.
Your advice would be most welcome, as this problem is very odd. Thank you.