Too many of the videos and advice at Adobe do not keep up to date.
I want to make Epub files from ID document files. I have a book - completed, it is all text, ready to print. I have tried several methods: the first is to add the complete file to create one Article - that doesn't allow me to create contents pages etc, nor is it acceptable to most epub sites.
The second is to paste each Chapter in turn to a new ID document, and then pull the first page of the Chapter across to the Article box - I name it but it still labels as Chapter Two each time.
Thirdly I create a new Article for each chapter but don't add any description in the Articles box - that doesn't work either.
From a book file, the best way is to use the Book panel menu and choose Export Book to EPUB.