I agree with Whiteroom except about the feet wide apart. The correct leg width is with the legs coming straight down from the hip sockets. Walking width and skiing width are the same.* When he describes shortening the inside leg on a turn so there isn't too much weight on the inside ski, that doesn't change the width between the legs.
So...stand easy on the balls of your feet. Do not try to pressure the boot tongues with your shins by squatting, that's too much work and locks you into an ineffective position. Stand on the balls of your feet and hinge forward at your ankles. While moving there is no difference between having the body forward or the feet back, but there is a big difference in how that is achieved. Our legs have three strong hamstring muscles that can pull our feet backward with ease. As you begin each turn strongly pull both feet back. You'll find out how far you need to pull them back depending on the steepness of the pitch, the tightness of your turn, and the characteristics of your skis.
And, some skis just chatter due to their less-than-perfect internal design & construction.
*exceptions for stance width---an unaligned bow legged skier needs the feet wider apart. An unaligned knock kneed skier need the feet very close together. A skier with sloppy loose boots needs a wide stance for stability. A skier with good natural alignment or correctly aligned by a good boot fitter in boots that fit uses the natural walking-width stance.