How do I use Bill Pay in the mobile app? Log in to your mobile app and select the “Payments” tab. If you are unable to see this tab, you will need to sign up for Bill Payer on your personal computer. Have more questions? Submit a request 0 Comments Article is closed for comments. Related articles How do I pay a 3Rivers loan/credit card/mortgage/line of credit? Can I enter new payees for bill pay through mobile bill pay? What will I find on the app’s menus? Mastercard debit card or Mastercard Credit Card was lost or stolen. Who should I call?