The Opportunities Preferences screen can be accessed from your dashboard by clicking on the ellipsis ( ⋮ ) on your Opportunities App and selecting Preferences.
This will take you to the Opportunities Preferences Screen:
There are two default settings you can set in the opportunity preferences:
Email Notification Template: When an opportunity is created, if you've assigned it to a different Method:CRM user, you're given the option to send an email notification to that user. This allows you to set the email template for the notification email. To create your own, check out Create a basic email template.
Default Opportunity Status: The default status for the opportunity when first created.