You can edit alerts you've set up by clicking on the pencil icon under the "My Alerts" section. Clicking on the settings cog ...

For general settings like enabling or disabling alerts, head to your phone's settings menu. Select Notifications or Apps and ...

You can set the notifications for all your courses or you can set ... you can decide when the notification will be sent out for that type of alert by clicking the icon.

Hit the blue "Update alert" box. And if you want to have all your alerts delivered at a specific time, hit the gear icon to the right of the words "My alerts" and choose a time for delivery.