To change your payment method, go to Settings > Subscriptions and Billing, then select Edit next to your current payment method.
From there, you can update or switch to a new payment method and save your changes.
Just to make sure I'm pointing you in the right direction, are you trying to change the payment method for your QuickBooks subscription, or are you looking to update a payment method used for transactions/invoices within QuickBooks?
If you meant something different, feel free to share more details and we'll be happy to assist you further!