Hi, Elitecleaning.
I can share details of how your customer can pay their invoices online.
There are a couple of ways to allow your customer to pay their invoice online. You can set up PayPal or GoCardless account so they can pay their invoice by card. To learn more about the integration, please click each link: Paypal and GoCardless.
Also, you can visit our third-party app page to find an application that suits your business need. Once decided, just click the Get app now button to integrate it in QuickBooks Online.
In addition, you can check out this article about how to void or refund payments for your future reference: Void or refund customer payments in QuickBooks Online.
You can add more details below if you have further questions about handling invoice payment. I'll be more than happy to help you again.