DIGITS doesn't have an setting within the app to manage the notification sound. If you're looking to change the SMS tone for example, you'd have to use the phone's pre-installed settings. If you want to set up different ringtones for different digits, our internal teams have collected examples of this already. As of right now, I don't have any new info about that option being available.
This thread was the product of our fantastic collaborators during DIGITS Beta! As many terms have changed and bugs have been exterminated since the Beta launched, the information here may no longer be accurate. If you still have a question, please search our active threads or ask a new question in the DIGITS space!