We need to create an invoice that shows the down payment as the total due and then total as the entire job cost

Creating an invoice that shows the down payment is my priority, @jill42. This way, you're able to keep track of your job cost in QuickBooks Online (QBO).

Based on your scenario, you can either record the down payment to your invoice as a line item or a retainer. If you choose to add it as a line item, you'll first have to add a new product or service item that you don't plan to track inventory for. Then, add it to your invoice as many times as you need. Here's how:

1. Go to the Sales menu and select the Products and services tab.
2. Select New.
3. Choose either Non-inventory or Service.
4. Add a name (i.e., Down Payment 50%). 
5. Enter all other necessary details.
6. When you're done, select Save and Close. 

Then, apply the down payment item to your invoice as a negative amount (i.e., -50). This way, you're able to change the total to the 50% down payment price. Please see the screenshot below for your reference.

If you opt to record the down payment as a deposit or retainer, I'd recommend checking out this article for the step-by-step guide: Record a retainer or deposit.

With QBO, you're able to create attractive and professional-looking invoices. This tool will let you add info that matters most to your business. To know more about this, you can refer to this article: Customize invoices, estimates, and sales receipts in QuickBooks Online.

Also, I'm adding this article to further guide you in using projects to track your project/job's profitability in QBO: Set up and create projects in QuickBooks Online.

Let me know in the comments if you have other concerns about recording down payments on your invoices in QBO. I'll gladly help. Take care, and I wish you continued success, @jill42.