You can change the date Digit sends funds from your expense goals to your biller at any time. Please note that it can take 2 - 5 business days for the payment to be applied to your credit card/student loan account.
Changing the Credit Card and Student Loan goal payment date
1) Tap into the goal you want to edit
2) Tap Settings
3) Tap Manage Payments
4) Select your new payment date, and tap Save
Changing the Phone Bill goal payment date
At this time there isn't a way to edit the payment date for Phone Bill goals since those work a bit differently than the student loan and credit card ones.
If you need to make changes to your Phone Bill's due date or billing account, you can delete that goal and start a new one.