The data source editor currently retrieves the passwords in encrypted form and attempts to save that encrypted value as the new password. The UI should be modified to not provide the password during save unless the user actually changes the password field.
I was decided to let the encrypted value retrieved be when the data source details page is opened to be resubmitted during save.. If the submitted password is already encrypted then not change is made on the back end. When the password arrives unencrypted then it means it has been changed by the user.