Hi there, @nancyl.

Right now, there isn't a way to create your own item type. You can only choose from the ones available in QuickBooks.

If you only want to show payments/credits on the invoices without affecting the transaction and any reports, you can put them in the Message field. You can rename the section header to Memo (Customize Data Layout > Footer). (See the 5th photo in my original answer above) However, you would need to manually type in the information every time.

I'd be glad to hear back from you if you have any follow-up questions.