Custom Template not used if invoice is emailed

Summary

The Fusion invoice is being sent from email, rather than custom template

Content

Hello:

We recently had a customer request an emailed invoice rather than mailed.  The emailed invoice had Infustion's name on it, rather than our customized invoice.  Can someone tell me where we need to indicate we want the emailed invoices to use our customized template?

Thanks for any guidance!