Stupid question... strike zone

[SamG]

I've got some conflicting information and know you guys would have the answer.

I'm not an ump, just a softball parent.

Regarding the strike zone... I was under the impression (and I think this is how I read the rule) it's a 'box' directly above home plate, from the armpits/numbers to the knees of the batter.

This weekend, someone (who I would trust knowing this... former NAIA coach and current NCAA 'advisor') told me if the batter is forward or back in the box, the PU "mentally" moves the plate so it's even with the batter.

For example, let's say the batter is all the way back in the box (front foot even with the back corner of the plate). A ball crosses the front corner of the plate "knee high", but drops off and hits the back corner of the plate. That's still a 'strike', right? It's the batter's responsibility to position themselves, right?

Does it matter on rule set? I wouldn't think so, but maybe this person is thinking NCAA and my DD plays NSA.

Sorry for the stupid question, but inquiring minds want to know.

Thanks