Click the settings icon in the top menu bar.
Click 'Settings' in the drop-down menu.
On the Settings page, click 'Emails' in the navigation menu on the left.
One the 'Configure your email subject lines' page, edit the text boxes to change the subject lines of emails sent out to your learners in each different instance.
Once your are finished editing the email subject lines, click 'Save' to keep your changes.