Extra Thumb Positions
This information will allow you to take control of the sound and can be applied to any ukulele style.
The photo Thumb Position 2, shows the thumb higher up the ukulele and from this changed position the emphasis will be on the G and C strings being struck with the force of the flick while the E and A strings will receive less of the power.
The photo Thumb Position 3, shows the knuckle of the thumb moved forward (pivot it on the nail of the thumb at the same time as you push your wrist forward) away from the body of the ukulele. From this changed position the emphasis of the flick will be on the E and A strings, the C string will be sounded but with not as much emphasis - the sound will be brighter.
Experiment with the different positions and you will soon learn what is the best position for you. Play the same chord in the different positions and hear the difference.