Firstly, play it as-as for awhile to determine if: a) it is too hard to press strings at the 1st fret, or b) is it really too high "up the neck."
Do buy a 6" machinist scale (a 6" metal ruler) and measure before sanding or filing anything.
Ukulelemate.com suggests: The distance between the strings and the 12th fret should be 2.5mm to 3.0mm in height.
In my limited experience the nut slots, which affect 1st fret feel, are where adjustment is needed. They are intentionally set high, as once you file them lower you can't go back. Same for the saddle. Caution: Each string is different. Nut slot filing errors are non-forgiving.
Do not rush out to find sandpaper for the saddle and frets or tiny files for fret ends and the nut and just go at it. Over the years, I have destroyed more than a few instruments this way by not knowing what I was trying to fix, or how to do it.
Yes, I finally learned (to an extent), but I did relegate some otherwise very playable ukes to the burn pile.
-Wiggy