I cannot for the life of me find how to edit that topbar in either behavior or content. I’m looking all over the backend dashboard, the files in Visual Code and the documentation, and I see nothing.
The most basic way to edit the content of the top bar is to add or remove pages from the navigation. An important base concept of TYPO3 is that the navigation should mirror the structure in the page tree. The Getting Started with TYPO3 video explains some basic concepts of the content management system. I have linked directly to the section that shows how the page tree in the backend is connected to the menu in the frontend:
Change how the top bar looks (TypoScript)
If you want to change how the top bar looks (without editing files), you can use the TypoScript Constant Editor. First select “TypoScript” module, then click on your site’s root page, and then on the “Introduction Package” TypoScript template.
Now you can use the “Selected category” menu to select different sets of configurations concerning how your site looks and functions, such as “bootstrap package: navigation”.
Select “Bootstrap package: full package” in the rightmost column. It will appear in the leftmost column to indicate that this site set is now made available in your site.
Now, click the “Save” button at the top of the screen.