Great day to you, service,
Let me get the help you need to ensure that you’d be able to add a bank account.
There are two ways to connect your bank account in QuickBooks Online. You can either go through the Accounting tab or via the Banking tab.
To create a new account through the Accounting tab. Here’s what you’ll need to do:
Once done, make sure that once you’ve created refund, you select the correct bank account.
However, if you’d want to sync bank account into your QuickBooks Online account so your transactions are downloaded automatically, here’s a great resource with guidelines: Connect bank accounts and manage imported transactions.
Please don’t hesitate to reach back out if there’s anything else I can do for you in adding a bank account, I’m always here to help. Have a wonderful day!