Hi @JamaicaA - The double payment didn't show until I followed these original steps to mark the invoice as paid. 

To start, let's check a few things before linking a deposit to an invoice. These are the following:

• Ensure you've created an invoice for the customer.
• Verify that the payment hasn't been entered and linked to the invoice.
• Make sure the payment was entered through Bank Deposit and not through Receive Payment.

Once verified, let's find the deposit entry on your bank register, here's how:

1. In the left menu, click Accounting. 
2. Go to the Chart of Accounts tab. 
3. Locate the account you deposited the payment to and select Account history.
4. Find and select the correct deposit.
5. Click Edit.
6. In the Add funds to this deposit section, find the deposit.
7. Choose the Received From ▼ dropdown, and select the customer the deposit was from.
8. In the Account ▼ dropdown, select Accounts Receivable.
9. Choose Save and Close.

After that, to apply the deposit entry as an invoice payment, let me show you what to do:

1. In the left menu, click the + New button.
2. Choose Receive Payment.
3. Select the Customer from the ▼ dropdown. 
4. In the Payment date field, enter the day you received the payment.
5. Go to the Outstanding Transactions section, select the invoice you need to mark as paid.
6. Under Credits, select the deposit.
7. Select Save and Close.

That's it! You're now able to link a deposit to an invoice. 

To share more detail, I had already created the invoice and marked received the payment via a zelle payment to my checking account. I have my bank account synced with Quickbooks, and the zelle payment went directly into my checking. I've read more into this and am wondering if my deposits should first go to "undeposited funds". If so, can you please advise on this? Thanks