How do you allocate a credit card receipt for an invoice against the invoice?

I'm happy to see you here in the Community forum, leon3.

If your trying to match the downloaded credit card receipt to your invoice. Here's what you'll need to do:

1. Click Banking in the left menu. 
2. Select the account you want to review.
3. Go to the For Review tab. 
4. Locate and select the credit card receipt transaction to expand the view.
5. Review the “Records found.” These transactions are ones you already entered in QuickBooks. 
6. Choose the link next to each record to get more details. 
7.  Review the “Deposit to” field on the forms. Your transaction in QuickBooks is already in the account listed. 
8. Hit Match when done. 

For detailed step by step process, you can check this article: Download, match, and categorise your bank transactions in QuickBooks Online.

However, if you mean something else, let me know and provide more details. I'm here for you. Have a great day.