I made a custom list and I'd like to go back into one of the sections and make a correction, but I don't see a way to do that. The only thing I seem to be able to do is make new sections, which isn't what I want. Please help

If you have not published the list you can do any correction. I guess that you have published the list and then you can't change. If it is not published you only need to click on any of the sections and then add/remove the words and or edit any entries. Think that you need to mail Nick if you need to change published lists.