Hello,
I'm not sure if this will work with your data, but you can try ordering the pass/fall column using a Value Ordering or List Check column property. You can swap the ordering with the Reverse button shown below.
This will change the ordering of the overlay in the legend. If that's a problem, you can reorder the legend in the legend settings dialog using the arrows shown below.
I hope this helps.
~John
P.S. If you would like to see both the pass and fail markers at the same time, you can change the fail marker shape to a hollow shape by right-clicking on the fail marker in the legend, clicking on Marker, then choose a hollow shape from the marker shape palette.