I understand the importance of setting up a payment account in QuickBooks Online, @mrclementllc-gma. I'll go over some details and tips about it.
Only the QBO US version can set up QuickBooks Payments. I recommend looking for a third-party application that you can integrate with QBO allows you to process customer payments smoothly.
For future reference, see these modules to find out how to handle payments and personalize invoices in QBO.