Hello Dave, thanks for taking the time to reply, really appreciated. The file I was trying to upload to YouTube had the MP4 extension at the back of it.
I made the small slideshow and just clicked on Publish, then the YouTube button.
To add to the above, I converted the slideshow to MP4 then went into my YT account and managed to upload it. The problem I have now is the slideshow only uses part of the YT screen, whereas on my PC it is full size. I used the 16:9 aspect ration.