I've just gotten around to upgrading to Tinderbox 7, from somewhere back in the 5s, and I ended up spending just shy of forever trying to figure out why a document upgraded from the old version was behaving they way that it does.
The behavior I observed was that HTML exports of the document were still obeying the ExportURL preference that had been set in the V5 version of the document, but, V7 doesn't appear to expose any setting panes where that preference could be changed.
This seems like a bug, or at least a missing feature. Since the Find function doesn't search the preferences (especially not unexposed ones) and it also doesn't search the Attributes, I ended up spending ages manually digging through the attributes for each of several hundred notes, trying to find where I might have embedded the base URL that was being magically pre-pended on exports. Of course, it wasn't there, but since Find couldn't tell me that, I wasted time looking. I only figured out the existence of the legacy preference by dumb luck when it finally occurred to me to attack the .tbx file with a raw text editor.
Anyway - someone may wish, sometime, to document the unexposed preferences that exist in the .tbx file - especially the ones that were previously exposed, and that may affect upgraded documents with no obvious way to change their settings.