When I log on, the same N number (for the first airplane I ever searched for) consistently shows up, as if I had “saved” it. How do I “undo” this feature, and how to I “do” the feature?
It shouldn’t do this. Did you perhaps bookmark that particular page?
It’s sounds to me as if jdoorlag is describing his browser autofilling the search form entry box, not actually pulling up the result page for that tail number. If that’s the case, it would be a setting local to your browser that’s trying to be helpful by filling in the value you first used.
What browser are you using?