Shane,
Sorry my answer was a bit convoluted.
What menus are you seeing? Are you viewing the screen or editing it? What you need to do is VIEW the screen that was made for the dropdown. You will see an option to view the screen to the left on the Customize > Screens tab link. When you do that, it will bring up the screen just like any other screen in Method, and from there you should be able to edit the choices.
The first screen is to show you how to view a screen from the screen list.
This next screen is a screen shot of a basic screen that was created by Method when a dropdown was added to a table. If you based your dropdown on a new table, a screen like this one would be created.
Hopefully, this will put you in the right direction.
- Adam