Hey Kevin, thanks for joining the membership!

The FL Studio scale highlighting can be found under View -> Helpers -> Scale Highlighting.. Helpers used to be its own menu in FL Studio, but now it is under the View option.

(Note, you can RIGHT-CLICK an option to keep menu windows open to save time when testing things out!!!!)

I believe you have to select a scale first (use right-click), then you can select your key.

Within the piano roll, you’ll be able to see the highlighted areas sharing what notes are within that scale..

Maybe I’m not understanding your question very well.. but that should be all that is required for how to use the scale highlighting in FL Studio!