When logging into NC State Services Duo will prompt you for your last-used authentication method. If you select an option and authenticate with it, Duo will remember and continue to automatically prompt you with that method until you use a different method. This preference is remembered per browser per device and is stored with a browser cookie. You may not be presented with the Universal Prompt to switch your method used if you are currently in a 14 day remembered device session. If this is the case you can wait out the remaining time and make a new choice when prompted for Duo in the future, or you can clear your cache and cookies for your browser on that device and then start a new login.
Once you complete this login, future logins from this browser and device will default to this method.