Hi There,
Sorry for the delayed response here, look like I missed your reply. You can specify which templates are used for which type of task (ie Invoices, Estimates, activities etc...) by selecting the Preferences snapshot of the App you are trying to set the DEfault template for.
For example, you want to set a particular email template for Sales Orders. you would navigate to your Dashboard, scroll down until you see the Sales Orders Tile, and click on the Preferences snapshot beneath it. From the Preferences screen, you can set which email template is used for Notifications for this app.
Hopefully this helps. If you have any questions regarding general Method usage, please feel free to reach out to your account manager or Success coach and they would be happy to assist!
Regards,
Ben