I have a modern leather sectional sofa with a low fixed back. Every time I try to put a decorative pillow on it, it either looks ginormous against the low back or it just slides off on the leather.

I did a Houzz search for "leather sofa" in "Modern Living Rooms" expecting to prove to myself that I don't need pillows, and to my great surprise most of them had pillows.

Any idea what I'm doing wrong?