If you are logged into your Express account, there are two places where you can edit your bank account from the dashboard:
In the Account tab under Payout Details
In the Payouts tab under the Balance Summary
Once you click on the Edit button, Stripe will send you an SMS with an authorization code and prompt you to enter it on the Dashboard page. Once the authorization code is verified, you can then update your bank account.
If you are having trouble logging in to your Express dashboard, you will need to reach out to the platform directly, as Stripe is unable to provide login links.