Nit: Why do I see different file icons for my Scrivener files in Finder? This is on my Mac. All files are updated and have been used with Scrivener 3.
Scrivener 3 / MAC High Sierra / iOS (iPhone / iPad
This is down to how Quick Look works (which is responsible for creating icon previews in the Finder as well as full Quick Look previews). You say that all files have been opened in Scrivener 3, but I’m guessing that the third one in your list has not yet been edited and saved in Scrivener 3, and was probably created in the iOS version (or perhaps it’s a new project that has not yet been saved).
The third in the list is Scrivener’s default project icon. That is the icon registered with the system as the icon for “.scriv” files. However, as with most apps, .scriv projects usually use a dynamically-generated icon. This shows the “S” in the middle and has the author name and book title above it, a little like a book title page. This can only be shown if the project has been edited in Scrivener 3, though. If it has not - for instance because the file has so far only been edited on iOS - then macOS falls back on showing the default .scriv icon.
All the best,
Keith
Thank you Keith.