I am in the outliner, all the folders have been disclosed… and I just wish the folders rows would be of a slight different colour, or otherwise differentiated, so that it’s easier on the eyes.
Preferences > Appearance:
Thank you for your prompt reply, but I meant the folder row to be of a different colour or better yet bold in style (in order not to compete with the alternate colour style) so that it is differentiated from the documents rows.
In that case, just look a little further down those very same Appearance preferences:
It’s generally a good idea to poke through the Preferences - there’s a lot there!
… but the preferences are scary! Like this “Lucidia” that I see in your screen cap. Sounds sinister to me. 
I have been told not to poke scary stuff…
Sorry, my bad. It seems Scrivener has been taken care of everything!