how to apply a template on several chapters

The method of choice is to create a temporary book

Select all files in the book window and import the formats.

This may not be more effective for less files compared with the "one file at a time" method, but for more files it definitely useful.

I think I have found what was the cause of my problem : my chapters were set in double sided page (for the pagination), but not the template (single side). So I have set the template in double sided page, and re-import the format in the chapters, and it seems to be working now.

I have succeeded to do it this afternoon, but tonight I don't know why but it does not work to apply page numbering at the top of some pages.

1) my template has one page and page number at the top of the template.

2) my chapters are set to begin each chapter in an odd page + numbering and pagination of chapters + Update.

3) I have made File/Import/Format with the name of the template + Update.

Result : I can see the page number at the top of the odd pages (but not at the top of even pages). Why ?

Because actually, to set a page number on the pages of my book, I have to open each chapter and go to master page where at the top I put the symbol # .

I would like to set the whole book in order it puts the symbol #  at the top of the page of each chapter, in one go.