Normally, holding
S while dragging the mouse and holding Left Click will change the scale like this. I don't know how you got it to do it by default.
Maybe your S key is stuck down, or something? Try pressing it a few times while you're in the CS, see if you can reset it, so that Left Click goes back to it's normal function of dragging objects.
As far as I know, there is no way to configure the CS controls manually.