I have 2 problems.1. I've marked an invoice as paid but it is still showing as unpaid.2. I edited an invoice and it has been processed as paid.

Hello there. I'm here to help you fix your invoice concern.

In this case, if you already marked the invoice as paid but it still shows unpaid, you can delete and recreate the invoice and then receive payment. Once the invoice is recreated, you can link it to the invoice payment.
 

Here's how:
 

1. Click on + New and choose Receive payment.
2. Select the customer from the dropdown.
3. Enter the day you received the payment in the Payment date field.
4. In the Outstanding Transactions section, select the invoice you need to mark as paid.
5. Under Credits, select the deposit.
6. Then, select Save and Close.
7.  

You can refer to this article for more details: Record invoice payments in QuickBooks Online.

On the other hand, with your problem number two, it's possible that there's a credit that has been applied automatically to the invoice. To learn more about automatically applying credits to an invoice, see the following articles:
 

• Create and apply adjustment notes or delayed credits in QuickBooks Online
• Handle a customer credit or overpayment in QuickBooks Online

I've also added the following articles for future guidance:

• Categorise and match online bank transactions in QuickBooks Online
• Reconcile an account in QuickBooks Online

Feel free to post a response below if you have clarification or additional information about managing invoices in QuickBooks Online. I'll be around. Take care!