Thank you for responding! I am on a MAC desktop. I have attached a screen shot.
I assume there is a proper name for what I am describing as a "notebook sidebar" but I can't find it easily. I am calling columns "sidebars", essentially. On the leftmost column is the "true" sidebar, in its collapsed version. This menu lets you search for starred items, switch views, search tags, dig in the trash, etc. I am talking about this sidebar when it is in "all notes" mode (the note icon.) This sidebar is minimized to 1cm wide in my screen shot.
The column one over to the right from the left-most sidebar column I call the "notebook sidebar." It displays notebooks in various views, with three options.
1) list mode (crono, name, etc in my case by "date created")
2) view mode: in my screenshot "card view" though it also could have just as easily been "side list view" or "Top list view".
3) Tags. self explanatory.
These three view options are what I consider the view options of the "notebook sidebar", i.e., the column with the notebooks in it. I don't see a way to get RID of this column (aka sidebar) or minimize it. That's what I want to do - minimize or hide it.
The third column over is the note itself, which is all I'm really concerned with. I don't want to see the 2nd column ("notebook sidebar") and would like to at least collapse it to the same slim margins of the "true" sidebar.
Hope this makes sense.