Thanks Mr.F. for your reply. I want to go through “all that trouble”, because I want to change things differently in those sections, using the “on all pages in this section” possibility.
Of course I already made a copy of the site and am working with that one. The site was created over a longer period, so there was no real initial planning - which I like to correct now.
But I have a question: How do I move pages in the Layers panel into the section? I seems, I can move them in the Pages panel, but only see that they are in the section, when I hide that section. Is that correct?
I think, there should be more information about sections.