Why do they say to lower your thumb?
The truth is, it’s less about the thumb and more about the way that moves your palm under the neck, the space that creates and the way that improves the angle that it puts your fingers in. Watch the video below to see how much easier it makes things for your fingers.
How The Thumb Guitar Trick Really Works
Article and video on how moving the thumb lower helps guitarists get their fingers in position to play guitar easier.