A credit is given to a customer to obtain goods or services before payment based on the trust that a payment will be made in the future. So, if your customer returns an order or complains about a purchased product, you can possibly make adjustments by giving customer credit in his next order. You can basically do this by creating a credit memo for your customer.
To do so in QuickBooks, you can click Create, which will lead you to the Credit Memo option. In here, you enter the customer’s name and the notification of what is being returned or what the credit is for. If your customer overpays you or pays you in advance for the goods he ordered, you must click on Create, then look for Receive Payment option. If the payment is more than the amount due on the goods ordered, the difference will be considered as a credit.
Also, in QuickBooks, there is the Apply Credit Settings that you can turn on and off if you so desire. To turn this on, go to Gear, then proceed to Company Setting, then choose Advanced then click on Automatically apply credits. This way, a credit will be automatically be applied on the customer’s next invoice. You can turn this setting off if you are creating many invoices and credit memos for customers, a specific credit memos need be applied to specific invoices.