[Koha] Add record author field locked?

Hi, We are using Koha in a small school now. One of my last hurdles is adding new books to Koha. We were able to add about half of the new books we have through Z39 searches but the remaining books (about 100) aren't being found. In trying to add these by hand I am running into a problem in that I can't add the authors name to the catalog entry for a book. That field is showing as locked. I haven't been able to figure out how to change that. Any help would be appreciated. Thanks, Shawn