When I first started, I created Square Invoices for a customar. She paid the invoice via square, but I am unable to apply it to the Invoice I have i Quickbooks. help?

It's nice to see you here in the Community, @christine5.

That's a great question! I'm here to share some information about applying for or receiving payments from Square to QuickBooks Online (QBO).

Are you using the Sync with Square app? If so, you don’t need to create any transactions in QBO for Square payments because after you activate this connection, all your Square transactions will be automatically imported to QBO.

In this case, since you already created invoices for your customer/client in QBO, you can just delete them to avoid duplicate transactions. Here's how:

1. Go to the Sales menu at the left panel, then pick Invoices.
2. Locate the invoice(s) of that specific customer/client.
3. On the ACTION column, click the drop-down beside Receive Payment.
4. Choose Delete, then Yes.

I also added a sample screenshot below for your reference.

To know more about the Sync with Square app, you may check out this article: Sync with Square Hub.

That's it! Please let me know how it goes or if you're referring to something else by leaving a comment. I'm only a post away should you have any additional questions. Have a great rest of the day!