I run multiple websites and I want to generate invoices from quickbooks from each brand.

I have created an invoice template for each brand in quickbooks, but the customisation fields don't seem to be working properly.
Whenever I change any of the company details on any template, it changes it on all the others templates as well.

I have spoken to QB support, but all I got from them was "that's how it is designed", which doesn't make any sense.

Why would you design it so that it intentionally doesn't work?

that is like designing a door that won't open and close.