The Sales Receipt App Preferences screen can be accessed from your dashboard by clicking on the vertical ellipsis (⋮) on your Sales Receipts App and selecting Preferences.
When a sales receipt is created, you are given the option to print or email it to the customer or lead it's been assigned to.
Email Notification Template: Email Template used when clicking the Email button on the sales receipt, which sends an email to the customer. To edit this template, go to Method:CRM's Send Email App, and select Edit Templates.
Email Outgoing Activity Type: When an email is sent to the customer via the Email button, an activity is created. The activity type is set to this dropdown.
Print Template: When the Print button is clicked on the invoice, a PDF file will be created and will use the template chosen here. To edit this template, you need to use Method:CRM's Report Designer tool.
Note, when these dropdowns are blank, then the defaults are used.