I've got some information about reverting to the old invoice layout, jlrrv.

QuickBooks Online has been rolling out updates about the new estimate and invoice experience. Since April 24, Simple Start and Essential plans users have been migrated with no option to go back to the old layout. With this, it's important to note that the option to capture signatures is not available with the new layout. You can consider using a third-party application to help you with your business needs.  

Furthermore, let's address the issue of having to search for a customer again despite creating an invoice from their profile. A cache-related problem could be causing some pages in QuickBooks Online to not load properly. Let's isolate this issue by opening your QuickBooks Online company in a private browser. From there, create an invoice from your customer's profile. If everything works smoothly and the customer's name automatically populates the invoice, I recommend going back to your regular browser to clear its cache. The same steps should also resolve the issue of your invoice showing up under the customer profile. You can also use other supported browsers.

You can check out this article for more information on the new estimate and invoice layout: See what’s new with estimates and invoices in QuickBooks Online.

Once you've successfully invoiced your customer, here's a guide on recording their payments in QuickBooks: Record invoice payments in QuickBooks Online.

Come back to this post if you have any other concerns about invoicing in the new experience. I'll be around to address them. Keep safe.