The way most of us do it (copied from another forum):

If you control-click a fretboard's handle you'll see "Edit Fretboard". Then you can "Edit Instrument" and click the "Available" pop-down and select ukulele. This does them one at a time. Someone else may know a way to change them all at once, but once you have done 3 or 4 chords you can copy and paste.

If there's anything newer, I don't know it.

It's a bit surprising that Finale doesn't already have built-in ukulele instrument chord diagrams considering its extensive library. 

This person (a.i.?) should be banned. Nonsensical answers to five year old posts do no one any service.