Why is it, on my bank statement I can see I have received payment from my customer. However, the invoice still shows as unpaid?

Hello, simone. 

Outstanding or unpaid happens when the payment is not linked properly to the transaction. To check this, open the payment and see if it is correctly applied to the sales entry.

Successful payments should display a Paid watermark on the invoice. If you see this yet still shows unpaid, follow the steps below to resolve it:

1. On the invoice, click the payment link below the Payment Status.
2. Select the payment date to open the Receive Payment window.
3. Refresh the payment by removing the check mark beside the Invoice Number and adding it again before saving.
4. Press Yes to confirm the action.

If the invoice payment is recorded through bank deposit instead of receive payment we need to link them to an invoice. Doing so will mark the transaction as paid. 

1. Press + New then Receive Payment.
2. Add the client's name to see all open invoices and credits.
3. Update the Payment date, then select the invoice from the Outstanding Transactions section.
4. Under Credits, select the Deposit entry.
5. When you're done, hit Save and Close.

If these are downloaded payments, matching them will close out the transactions and keep your record in tiptop-shape. Once the transactions are downloaded, QBO suggests possible matches based on entries, such as payments from customers, so you don’t have to manually add them.

To find matching transactions, follow these steps:

1. On the Banking page, select the For Review tab.
2. Locate the payments.
3. Click the Find match option.
4. Locate the invoices and select them one by one.
5. Verify that the total of the selected transactions is the same as the amount of the downloaded payments.
6. Click on Save.

To help give you a better idea on how QBO match downloaded transactions to existing transactions, check out this article: How to add and match downloaded banking transactions.

You may refer to this resource as your guide in linking deposit: How to link a deposit to an invoice.

Please know that I'm just a post away if you need a hand managing customer transactions in QuickBooks. Wishing you and your business continued success.