On the Takeoff tab, click the stairway on the drawing canvas to select it. Then click Rotate in the Shape Edit group on the ribbon.
Move your mouse to swing the reference line. The red line and the stairway preview show the new orientation. When the stairway is positioned the way you want (for example, horizontal), click to confirm.

The stairway is now rotated. The direction arrows and dimension labels (for example, 11" x 8 and 42") update to the new orientation.