Thank you for following this thread, Dode.

I know having accurate records of all transactions is important for your business. This will keep your bank in balance and ensures future payments are recorded correctly in your company.

Based on the scenario, you'll have to create a credit note and then apply it to future invoices. Before performing the process, make sure the Automation feature is not turned on. Doing so prevents QuickBooks from automatically applying credits to transactions.

I’ll help make sure you can do this in just a few clicks. Here’s how:

1. In your company, tap the Gear icon in the upper right and choose Account and settings under Your Company.
2. Head to the Advanced menu on the left panel and go to the Automation section.
3. From there, check if the Automatically apply credits feature is turned on.
4. If yes, move the slider for Automatially apply credits to the left to deactivate it.
5. Press Save and Done to apply the changes.

After checking the Automation settings, let's go ahead and enter the credit memo. Follow the steps below to do this one in your company.

1. Navigate to the New menu in the upper right to select Credit Memo under Customers.
2. Pick the customer's name in the Customer drop-down and input the credit memo details (amount and date).
3. Fill in the remaining fields.
4. Click Save and close to keep the entry.  

Once done, you can apply it to your invoices. I recommend following the instructions shared by @Rea_M above. For more insights into this process, tap here to view the complete details of the article. It provides information on when to create a credit memo or delayed credits.

In case you've already recorded one and it didn't show up in the customer's list, run the Invoices and Received Payments report. From there, check which entry it was applied to and unlink the credit note. This way, you can use it for the correct sales transaction.

Here's how:

1. Navigate to the Reports menu on the left panel and enter Invoices and Received Payments in the Find by report name field.
2. Set the correct date for the report.
3. Look for the credit note and click on it to see the transaction details.
4. In the Credit Memo screen, head to the Refund Status section and click the 1 payment made link and date to open the payment. 
5. Uncheck the invoice to unlink it to the credit note.
6. Click Save and close.  

For future reference, this reference contains a list of topics that tackles sales and customer-related transactions. These resources will guide you on how to handle customer payments, manage your clients' information, create sales entries, and process refunds or credits.

Reach out to me again if you have additional questions about processing a credit note and applying for future payments. I’ll jump right back in to answer them for you. Wishing your business continued success.