In any deflection equation, the cross-section of a beam is related to the area moment of inertia term. A key concept. Take the example of a rectangular cross-section, with the area moment of inertia being
I_{xx} = bh^3/12
Simply by looking at the equation, we know that changing the height would have a greater influence due to the quantity being tripled. This equation is applicable for the orientation of the rectangle shown in the image below.
If the rectangle was flipped on its side so that the h length is facing down,
I_{yy} = b^3h/12
would be applicable.
