Thanks for getting back to us, @vestaviat. As an additional inishgts, your invoices will automatically be posted on the default accounts in QuickBooks Online. 

These are the ones created when you set up your company. However, if you need to use more than one A/R account, QuickBooks will let you choose the A/R account you want to use when creating an invoice or receive a payment.

Here's how you can add accounts while recording an invoice. While you're in an open form, select the Category dropdown, then + Add new.

Learn more about adding an account to your chart of accounts in QuickBooks Online.

Let me know if you need more help. We're always around to assist.