It used to be that you could receive payment and create an overpayment to be applied later. When you would create an invoice you could click on apply credits and it would give the option to apply it. That very simple way of doing it (which I had been doing for over a decade) came to an end when I updated in 2020. I spent hours trying to figure it out and did a remote with a tech for several more hours. Long story was after getting higher up with techs it was a known problem that supposedly was going to receive a patch. It never has, which is ridiculous. Here's a link to that saga-

https://quickbooks.intuit.com/learn-support/en-us/payments/applying-credits-to-invoices/00/805547