How do I match a payment (debit ) against a supplier invoice(credit)

Hi there, jaysgov.

I'd be glad to help you match the payment to the invoice. Can you also tell us how was the transactions recorded? This is for us to make sure that we give you the right steps and information that are applicable to your case. 

In the meantime, you can use the Bill Payment feature to apply the payment to the supplier bill. I'd be glad to show you how: 

1. Open the bill or supplier invoice that you want to mark as paid.
2. Click Mark as paid in the upper-right hand corner.
3. Scroll-down to the Credits section and look for the payment, then check the box before it. 
4. Click Save and close. 

Here's an article about this for more details: Enter Bills and Record Bill Payments in QuickBooks Online.

If you're using the Online Banking feature, you can match the transactions together. 

Follow the steps in this article for more details: Categorise and Match Online Bank Transactions in QuickBooks Online.

Fee free to check out these articles in case you need more information when managing banking transactions in QBO:

• Unmatch Downloaded Bank Transactions or Move Them to Another Account 
• Undo or Remove Transactions from Reconciliations in QuickBooks Online 

The Community is always here if you need anything else.