To access settings click on the ... (more icon) to right of the name of the list, on the left navigation pane.
In the Staff Settings screen you can configure individual notifications as well as Page All notifications.
To create a Staff Notification or Page All message, click on the + icon next to it. A new row will appear to for you to enter the message.
To delete a message, simply click on the X on the row for it.
NOTE: You can protect these settings with a PIN.