There is a minor inconvenience and confusion for users when they add a new database. Just before submitting the form the user remembers that the database should be created under another subscription. Apparently the javascript counts on it that you follow the top-down order when filling out the form. When you change the subscription the other field content remains unchanged, which is good, but then the save button is greyed out! Apparently it "believes" that you should still fill out the other fields, but they are already, because the user simply decided to change the entry order, just correcting one error, namely the subscription.
The work around is that you add one character to the user name and then delete the added character again. The javascript will see the entry, validate the form and the save button becomes active. The fix would be that the form is not only validated when the text forms changed, but also when subscription changed.