Hi @rebecca.shane, the easiest solution would be to use the “slider” style in the Appearance tab, and set your ticks to 0,1. Or, just keep the rating style slider and only set the tick locations as 0,1. This will give you ratings between 0 and 1, but you could also use 0, 40 which will give you ratings between 0 and 40.
Btw, for your first question about changing the marker color, is this for an online study?