This is not the kind of service we want you to experience, @autosavefeaturenow.  

Currently, the option of auto save when creating an invoice or estimate are unavailable in QuickBooks Online.  

I understand the importance of this features to your business. Rest assured, I'll personally send this feedback to our product developers. This way, it might be given a chance to be added to our next products update. 

I suggest visiting our Blog site. This is where we share recent happenings and future developments, such as updates to newly added features. Here's the link:The QuickBooks Blog.  

Just in case, I added article for more detailed about Customizing invoices: Customize invoices, estimates, and sales receipts in QuickBooks Online. 

I'm just a post away if you should have any questions. Have a lovely day.