How can I match a customer receipt, in the bank feed which has already been marked paid on the customers records/list

Hello there, @karenl55.

I'm glad you've reached out to the Community. Let me share some information about matching transactions in QuickBooks Online (QBO). 

As long as the transaction that has already been marked as paid is not yet reconciled or cleared, you can still match it on a customer's receipt. 

For additional reference, you can check this article on how to match and categorise your downloaded bank transactions. 

If you need further assistance with the steps, I recommend contacting our QuickBooks Online Support Team. They have additional tools to pull up your account and do a screen-sharing.

Here's how to contact our customer support:

1. Sign in to your QuickBooks Online company.
2. Select Help (question mark icon) at the top right.
3. Select Contact us to connect with a live support agent.

For future reference, you can visit these articles to learn more about the bank feeds and reconciling a bank account:

• Manage your banking in QuickBooks Online UK.
• How to reconcile a bank account and common troubleshooting tips [Video].

This should get you on the right track. Feel free to leave a comment below if you additional questions about matching transactions. Wishing you and your business continued success. Have a good one.