You can change your linked bank account by following these steps.
1. In Messenger, tap 'Settings'
2. Then swipe to 'Bank'
3. Select 'Bank Account'
4. You will see the bank account you have currently linked, or a list of bank if you don't have any account linked. To change your account, tap 'Change account'. If your account is in error, the button will say 'Re-link account':
5. Select which account you want to link, or tap 'Link to another bank' to change banks completely.