How do I get back to the old format?

You don't.  They made it so everyone is permanently on this new, sucky format. 

I am not a fan of the new format either. The old one was so much better. They should still allow you to choose the old format.

We hear your feedback regarding the new invoice layout in QuickBooks Online (QBO), everyone.

As of May 6th, 2024, the option to revert to the old invoicing layout is no longer available in all QBO versions. With the new invoicing experience, QuickBooks ensures the product meets diverse business needs and enhances productivity. Rest assured, this will not affect your existing information and will remain accessible even after migrating to the new layout. See the QuickBooks Invoices and Estimates FAQs for more details.

In addition, this article will guide you through the features available in the new release of invoice and estimate layouts: See what’s new with estimates and invoices in QuickBooks Online.

Furthermore, you can read this article to learn how to personalize and add specific information to your invoice and other form styles in the program: Customize invoices, estimates, and sales receipts in QuickBooks Online.

Let me know if you need further clarification regarding the invoice layout update. We'll respond promptly to address them. Stay safe.

@Kevin_C   RE: We hear your feedback regarding the new invoice layout in QuickBooks Online (QBO), everyone.

It sure is nice that you 'hear' it, though that's not helpful at all, unless you actually do something about it.

nice that auickbooks can "hear" all the complaints about this update. PLEASE let us go back to being able choose for ourself! DO NOT LIKE THIS CHANGE AT ALL