Hello there, Parag. In the QuickBooks Online Australia version, the credit memo is referred to as an adjustment note. You can find and modify the amount from the customer's profile.
To create an Adjustment note, simply click Create or the + icon > Adjustment note. Enter the necessary details, then hit Save and close.
To edit the adjustment note, you can click All apps > Customer Hub > Customers > customer's name > Adjustment note transaction > Edit. You can then change the amount or add another PRODUCT/SERVICE and enter the necessary details. Click Save and close.
To learn more about applying the Adjustment note to an invoice, refer to this article for the detailed steps: Handle customer adjustment notes and delayed credits in QuickBooks Online.
Feel free to comment below if you have questions about the adjustment note in QuickBooks Online.
