Thanks for joining the thread, @angelacct. 

Instead of receiving payments from your customers, you can issue a credit memo. By this, we can apply the credit amount to their invoice, which will show up as a return in their account. By doing this, you can clear the amount from your accounts receivable and reduce your net profit.

Here's how: 

1. Select + New.
2. Select Credit memo.
3. From the Customer dropdown, select the customer's name.
4. Enter the credit memo details, such as the date and the amount.
5. Once done, select Save and close.

After creating the credit memo, it can be applied automatically to your invoices depending on if you've turned the settings on. Otherwise, here's how we can manually apply them to your invoice: 

1. Go to + New icon, then select Receive payment.
2. From the Customer dropdown, select the customer.
3. In the Outstanding Transactions section, select the open invoice you want to apply the credit memo.
4. In the Credits section, select the credit memos you want to apply.
5. For the open invoice in the Payment column, enter how much of the credit you want to apply.
6. Leave the Payment method, Reference no, Deposit to, and Amount received fields blank.
7. Fill out the rest of the form and ensure the total is correct after applying the credit memo.
8. Once done, select Save and close.

Furthermore, you'll want to check this article and learn how and when to give a credit memo or delayed credit to customers: Create and apply credit memos or delayed credits in QuickBooks Online.

Additionally, you can refer to this article for future reference if you want to learn how to personalize and add specific info to your sales forms: Customize invoices, estimates, and sales receipts in QuickBooks Online.

I'll leave this thread open for your comment if you need additional assistance managing your invoices in QuickBooks Online. Stay safe.