You can change your online banking username by following this walk-through.
Navigate to Settings by accessing the left hand menu.
Click on Security
Click on Change username. You may be prompted to enter your password as added security.
Enter your new username. You can click on Show rules to learn about what characters and length are allowed for the username. The system will validate the username in real time to make sure that it's not already in use and complies with the username requirements.
Click on Save. You will receive a confirmation banner on the top of your screen.