You can link a new bank account in the My Account page of your Catch user portal or while you are checking out with Catch on a brand's website.
In your My Account page: Log in to your Catch account and select My Account in the upper right corner. In your My Account page you'll have the option to edit linked payment methods.
During checkout: Once you've selected to pay with Catch and logged in using the secure phone PIN, but prior to completing the purchase you can select the pencil icon in the payment method box to link a new bank account.
Note that once a new bank account is linked, your original bank account will be forgotten by Catch. Only one bank account can be linked to your Catch account at a time.