I'll be happy to help! Managing your sales is an important side of your business. With QuickBooks Online, you can create professional invoices and send them to your customers in a few easy steps. If you wish to record a down payment while preparing an invoice, you can take advantage of the Deposit feature. To do so, follow these steps:
To know more about how to create an invoice, check this community article.
Let me know if you have any other questions.
It depends on how you recorded receiving the down payment to start with.
Typically you have a liability account for refundable deposits, and a service item linked to that account. You use that service item on a sales receipt to record receiving the deposit.
Then when you invoice, list all items being sold, list the deposit item, set the qty to negative one, and enter the amount of the deposit.