Ford EXPEDITION 2017 Owner's Manual page 197

Driving Aids
If the loaded vehicle is not moved for
approximately 12 hours, the leveling system
may bleed down to a lower height. This
can be especially apparent if a trailer is left
attached to the parked vehicle for long
periods of time. You must drive your vehicle
in order to re-level the suspension.
If a self-equalizing hitch is used, your
vehicle should be driven approximately
2 mi (3.2 km) with the trailer prior to
adjusting (leveling) the hitch.
194
Expedition (TB7) Canada/United States of America, enUSA, Edition date: 201604, Third Printing