Photoshop Undo 할 때 레이어 바뀌는 것 Layer changed

http://www.bigresource.com/Photoshop-Undo-more-then-one-step--Gq96vTGF.html

Q. Undo - More Then One Step?

In CS that I've just installed (yes, new to PS the ctrl-z only undo's 1 step backwards, what can I do to enable it to undo multiple times? Coming from PSP, you could undo for hundreds of steps....

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A. Step Backward And Step Forward
I have CTR-Z mapped to step backward.

Using two different shortcuts for "undo" (one step back) and "Step Backward" (Multiple steps back) makes no sense to me. As such, I rarely use the regular undo, and do not have it mapped.

The case:

When I switch to a new layer, do a brush stroke and undo it, photoshop treats my undo as a switch back to the layer I came from. This happens a LOT, and not just to me, but to a lot of designers I know (I'm a GUI designer at a game company). Some of them have even formed a habit of "erasing" a bit in an empty part of the layer, just in case the'd later want to undo. That's bad.

My proposed solution:

-First undo my stroke, Leave my selected layer alone.

-On a NEXT press of "Step backward" change my current layer to the one I came from.