Change styling of buttons in sequence drag and drop graded question in Storyline

Is it possible to change the look of the rounded button-looking markers for the built-in sequence drag and drop type graded question in Storyline? It appears there isn't because when I click on one and change the fill color it changes the fill color of what appears to be a rectangular box behind the rounded button-looking marker. I don't even see an option to change any states for them. I'd really like to customize these markers. Any ideas?