Hi Cindy,
We just released the change I mentioned a few minutes before I made my last post to this thread so I am not surprised that the listings you posted earlier today do not reflect this option, but I do expect the listings that you have already scheduled to post later today and tomorrow to reflect this option. Your assumption that you do not have to make any changes to the listings is correct.
If you do not see the "zoom" options in any of your listings that post after this adjustment was made, don't hesitate to let me know and I will be happy to take a look.
-Mike