At the moment we don’t have a way of setting up a default format per project, there is just the global setting in F12 (and yes, everything in there is for the whole program, projects do not use any of these settings exclusively). Projects do have settings, but you interface with them in the menus, such as splitting the interface, that’s a setting, or toggling label colours to tint icons. These sorts of settings are saved into the template when you use the File/Save as Template… menu command.
Generally speaking this isn’t too much of a problem since most people use the compiler to clean up the formatting of the document on export. As you’ve probably found out, unlike programs like Word that mimic the printed page, you really don’t have to worry too much about formatting for most forms of writing. The idea with the global setting is that one would choose whatever they find a comfortable font and paragraph settings for writing with. What the thing looks like when you print or send it off to another program for final polish can be entirely different from that—and that is the part that is saved per-project, in the Compile settings.
So for most things, and how the program was designed to be used, it really shouldn’t matter much at all what your text looks like while you write. It can even be a huge mess of different formats pasted in from other programs.
On scopes, I suppose you could break it out that way, but it seems overly complicated to me. I think a key thing that can simplify that list is a bit is the knowledge that the text editor simply stores whatever formatting has been attached to any text within it. When a document is brand new, and there is no text yet, it will use the application settings to start off, but once you’ve done that every single character in the document can have its own formatting. There is no setting for that beyond what you do with the buttons and rulers. There are no “scopes” beyond that, the only important thing is that the literal text stores the formatting, be that five paragraphs, one, a sentence or a single letter of the alphabet.
To make it even simpler: Scrivener’s editor works just like Word, LibreOffice, WordPerfect and even WordPad in these regards. You select five words and make them bold and they will stay bold. If you type inside of that phrase the stuff you type in will be bold. If you copy and paste to another document it will remain bold. If you change Scrivener’s settings for new document formatting, they will remain bold (and using the old settings since the text stores the settings, not the document). That latter point is perhaps the only major difference, but even there the difference is exceedingly slim, since you can adjust Word’s “default formatting” by editing the normal.dot file, and that won’t do a single thing to any of the many existing .docx files on your disk—only impact how new .docx files are made.