Welcome to the Community, eugenieg1. Let me help you save your work.
If you're trying to save your existing work as a draft, QuickBooks Online (QBO) doesn't have that option as of now. Instead, we can save and close your transaction by choosing one of the options from the dropdown button. With this, you can edit your work anytime.
Also, I've added a screenshot for your better visual reference.
Furthermore, you can check out this article if you want to personalize and add specific info to your sales forms: Customize invoices, estimates, and sales receipts in QBO.
If you have further questions or clarification about saving your work. Please don't hesitate to reply to this thread, the Community is open 24/7. Have a great day!