After opening the Prefs you are supported by a Search Preferences field in the bottom left of the window. This very handy feature lets you, as I assumed, search and find any occurrence of the search string on all the Prefs pages.
Wanting to change the scrollbar colours, I searched for "scrollbars":
This yields two results. But as it turns out the Display -> Colors and Fonts also has an option with the text "scrollbars" shown. But the search does not find this occurrence?
Am I missing something? Thanks.