To edit your notification settings, click on the drop-down toggle arrow in the upper right. Next, select "Account Settings" from the drop-down menu.
Within the Account Settings page, you're able to view all notifications options by clicking Notification Settings. Each setting seen can be toggled on or off, simply by clicking the corresponding box.
Upon settings being changed, the "Save Settings" button will appear in the Notification Settings window's upper right hand corner. Click this to update your settings!