Welcome to the forum Daveyfly
!
It is true that you may not shrink anything in TS4.
However, do you, instead, want a "shorter" set of stairs? If you do, then, the easiest way to do that is:
1. Place stairs before anything or much of anything is in your lot's house or yard --- preferably in an empty yard. Rotate the stairs with the move button (cluck on the stairs to get the move button).
2. To rotate anything, including stairs, move your mouse and your wrist. Along with the curved rotate arrows, you will see the move button with 4 strait arrows, so after you rotate the stairs, you can move them exactly where you want them.
Here are three screenshots, if that will help you. If you can't see the arrows in this screenshot, then, simply select the stairs, like I have done in this screenshot (tall stairs that you will get if you click on stairs to build them), and you will see the arrows.
tall stairs are shown at the very bottom of this post.
short stairs --- lower the foundation by clicking on the foundation in build mode. You will see a "slider" to adjust the height of your foundation. To get short stairs, just set the foundation height to about halfway up the slider.
side facing short stairs
front facing short stairs
I hope that this helps you out
!