About the only place I know of to adjust this would be in the Other Nicknames field. If you want it to explicitly show just Anne Whitwood Stevens as her original name, with her married name Anne Stevens Waterman, then you probably would not use the Middle Name field at all, and just leave her at Anne Stevens, married name Waterman, Nicknames "Anne Whitwood Stevens", "Anne Stevens Waterman".
It's either that, or just annotate it in the bio. The only other option would be for someone to rewrite the WikiTree code to fix this, as the current display options cause this. I've noticed this on quite a few profiles and had to adjust to accommodate the system.