My buttons are on top, not on bottom, but if I hover the mouse over them, the text says:
New note
New folder
Change sort order
Auto-reveal current file
Collapse all
So use button number 4 if you are in a note, and you have no idea where in your folders it is, and that folder should open to show you. Use button number 5 to close all of the folders in the list, so that you can see only the top level folders.
This doesn’t actually answer the question you asked, as I have no idea where in the instructions to find this information, but sometimes just playing with the program gives enough info.
Ooo, I just noticed that button number 4 stays pressed till you un-press it. This means that you can leave it always on, and as you jump through your notes following links, the folder and file list will either always show you were you are, or never show you where you are, as you prefer. Thanks for asking, and thus for making me notice this feature. I can think of times when I will prefer one state or the other, and it is nice to know we can so easily switch between them.