An AI summary (not always 100% accurate) states...
"There's no hidden or advanced editing feature found in NCH Express Invoice that enables users to create and title multiple default/template invoices with custom numbering schemes suitable for different customer categories. The numbering system is automatic and tied to the overall invoice system rather than individual templates.
The software allows creating invoices from existing quotes, orders, or draft invoices, and it supports saving invoices as drafts or recurring invoices, but these are not the same as having multiple distinct named templates for quick selection. Items and customer details can be saved and reused, but default templates themselves are not individually identifiable or editable beyond general invoice style customization."
You might file a suggestion with NCH.