Hi there, Joel Shee.

I'm glad to have you here and be able to help you out with your query.

Are referring to the Credits section when linking the invoice and to the other transaction. If so, the plan has nothing to do about it. Normally, we will be able to see an option under Credits. It's all depends on how you record the transaction to link it to the invoice. Let's say, you've recorded deposited transactions, or created a credit memo to link it to the invoice.

When following the steps below, we'll see deposit (e.g) Credit  and invoice under the Outstanding Transactions section. Here's how:

1. Go to Sales on the left panel.
2. Select the Customers tab. Then, click the name of the customer.
3. Under the Action column, click Receive payment.
4. Within the Receive payment page, you'll see the Invoice and Deposit transaction.
5. Make sure they are ticked. Once done, hit the Save and Close button at the bottom part of the page. 

In your case, it could be that you go directly to the Receive payment page. It goes like we click the +New button then, select the Receive invoice payment under Money in or Customer. If that's the case, we only have the Outstanding Transaction section since there's no other transaction that should link to it. 

Also, you may want to explore this article: View sales transactions. We can get additional information on how to manage the sales transaction within QuickBooks Online.
 

Let me know if you have follow-up questions about it. I'm always right here to guide and assist you further. Otherwise, you can enjoy the rest of your day. Stay safe, and be well!