While I was at home (Honolulu) this Summer, I attended the free ukulele lessons at the Royal Hawaiian Center -
Food Court (Tues thru Fri 10-11am).
I noticed that many of the newbies did NOT pivot their hands when moving from F to G7. Many had their thumbs
visible from behind the neck while they were trying to form the chords. Two lessons here:
1- keep your thumbs out of sight (generally) right smack behind the 2nd fret.
2- PIVOT your hand toward the head/tuners when moving from F (2010) to G7 (0212) or whenever you have to place
fingers below another one.
The same will be true (2) for forming F#m (G7 formation on strings 4,3,2/G,C,E).
I hope this helps.
And, if you're ever in Waikiki and have the opportunity, please go to the free ukulele lessons at the Royal
Hawaiian Center and tell the Aunties who are teaching, that Uncle Rod said, "Hi".
Keep uke'in',