I will go through the suggested steps to troubleshoot/resolve the issue, but have you tried this in QuickBooks Online? Does it work for you?

I followed your directions, and I have my custom invoice set as the default.  It still doesn't work as expected.

There are two options for creating invoices:

• Option 1 - "Create Invoice"
• Option 2 - "Import Invoices"

When using Option 1, the default/custom invoice is used, and all is good.  I don't use this option as I have hundreds of invoices to create regularly.  When using Option 2, the "Modern" invoice is used as the template.  I must have the "Account Summary" on the invoice.  The "Modern" invoice does not provide the option to include an "Account Summary".  I've been using Quickbooks for 15+ years, and a couple of years ago when Quickbooks changed the way invoices are created, the functionality for including an "Account Summary" on the "new format / Modern Invoice" was removed.

How do I get an Account Summary on either 1) The Modern Invoice (this is a quickbooks invoice that's included with Quickbooks Online), or 2) Imported Invoices.

Thanks for your help and looking forward to your reply.