Since everyone seems to want to be able to set this enabled by default...
- Log into your Admin Control Panel
- Go to User Profile Fields > User Profile Field Manager
- Locate the "Quote Notification" field, and click "Edit"
- In the big "Options" textbox, switch "Yes" and "No" so that "Yes" is first. This will make "Yes" the default option.
- Make sure the "Set Default" option is set to "Yes" as well
- Save your changes