Scrivener’s Preferences window and options (Scrivener>Preferences) have been streamlined. All of the old options are still there, but have been reorganized, and a few new things have been added. If you haven’t spent much time in the Preferences window, definitely check it out. You might be surprised at the behaviors and appearances you can change to meet your, er, preferences.
NOTE: If you want to copy over your preferences settings from Scirvener 2, see Transferring Your Preferences to Scrivener 3.