How to record a payment of multiple invoices all at once?

Welcome to the Community, @MJ12345.

Let me share some clarification about recording customer payments in QuickBooks Online.

If the invoices are all for the same customer, you can make the payment at once. You do it by clicking the + New option and selecting the Receive payment option.

For the detailed steps, here's how:

1. Click the + New option.
2. Select Receive payment.
3. Below Outstanding Transactions, put a checkmark on the invoices you want to pay.
4. Hit Save and close. 

Also, I've attached some articles you can use to know more about recording payments, as well as the way to undo this:

• Record invoice payments in QuickBooks Online
• Undo the Receive Payment of an invoice

Drop me a comment below if you have any other questions. I'll be more than happy to help. Wishing you a good one.