I just ran into some exceptionally helpful video by Gary Rosenzweig -- turns out his Macmost site has more than 1500 "how to" videos. They're friendly, step-by-step, and his narration is soothing. They're not captioned, but Gary's voice may have been one of the Google "auto caption" AI trainers, because they do an excellent job.

http://macmost.com
( Creating PDFs on iOS 10 and 11 )