I've got a 2017 NX and this helped a lot.
There are two settings for the power liftgate and they're set in different places/screens!
power liftgate on/off: set in the instrument cluster display (between tachometer and speedometer) using the steering wheel controls - as described above
power liftgate opening height: set this using the multimedia display (radio, etc.) and the control dial/pad next to the gear shift