look back

[MartyG]

Hello,
This is my first inquiry, so have patience with me, thanks. I would like to be as informed about the rules as I can be. I am reading the rule book and I am just not sure about some situations.
The look back rule is new to me. I need some clarification. When the pitcher is within the circle with the ball, all runners must precede to the next base or return to the previous base. There is no standing still. The runner gets only one stop.
If a runner commits to a base after the first stop there is no turning back. If she does turn back she is automatically out and the other runners still able to advance. (True or False)
If true, if we play on another runner does that wipe out the out?
If false, When a pitcher plays on a runner, all runners are then able to advance.
Please inform me where I might need some direction.
Thanks,
Marty.