Make sure you "click away" from the row you're editing to update the record. You'll see that the row indicator (black arrow-head on the left of the domain name) changes to a "caret" cursor when editing a row. When clicking on another row it will change from a caret to a curson, saving the row. As long as it stays a caret the row won't be saved.

As this behavior may be confusing, we will be changing this functinoality within the next few days to make it easier to save these settings.