please remember your thumb placement.
I believe your uke should NOT be resting in (or touching) the web of your fingering hand
(generally left hand) as your thumb should generally be hidden (from the front) at the
middle of the back of the neck behind the 2nd fret.
I see many beginners 'grasping' the neck with their fingering hand and not giving their fingers
enough room to properly form the chords, especially the 3 and 4-finger chords.
I'm not saying you may not or cannot hold your uke in the web of your chord-forming hand,
I'm just saying that if you're having difficulty forming chords and/or switching from chord to
chord smoothly and easily, it may have something to do with your thumb placement.
my 2 cents
keep uke'in',