The new invoice layout / Quickbooks interface  breaks custom templates in the IOS app. 

Instead of using whichever custom templates (invoice or estimate) you have set as default, the IOS app uses the regular Quickbooks version.

The temporary fix is to use the web app, and change the Quickbooks  back to the old style / platform. The IOS app then reverts to the old invoice version, which works fine.

But…I’ve realised this bug needs to be fixed before October, as the old style/platform will be discontinued.