First you should clarify "what you mean by tooltip" please, as we still are not sure what you mean
Did you mean the centered text above the compass, shown at my 1st screenshot as text "Welkwurz"?
I do not know any setting for that. I'd disable all addons and try without them if it is shown. Maybe some addon disables it for you.
Normally it should show if you change the view into the direction so it get's centered at the compass.