If you mean the image in the topic you linked to
<img
src="https://forum.keyboardmaestro.com/uploads/default/optimized/3X/2/7/27a90309b2f8e079db760d791744afa8b5cf4819_1_690x2000.png"
width="690" height="2000">
and you changed the width and height values, have you also tried changing the src value? i.e.
27a90309b2f8e079db760d791744afa8b5cf4819_1_690x2000.png
notice the “690x2000” in the name.