Hello there, debtscience.
If you want to update the bank account that receives the actual invoice payments, you'll have to update it through your QuickBooks Payments account. You can follow the steps to do it under the Update your bank deposit account section in this article: Update business and account information.
Note that if you change your account after 3 PM PST, we'll start using your new account the following business day. If you already processed payments prior to 3 PM PST that day, we'll put them in your old account.
After those updates, you can already send invoices and receive payments under the updated bank account.
If you're referring to the bank account that downloads your bank transactions, you can set up another connection for the updated one. You can use this link for reference: Connect bank and credit card accounts to QuickBooks Self-Employed.
Let us know if you need additional assistance with the process. Have a great day!