When you touch and hold a notification on the status bar, two options will appear “Prioritised” and “Silent”.
a) Select “Prioritised” to allow sound or vibration alerts for this app at subsequent new notifications.
b) Select “Silent” to mute all notifications from this app
You can go to “Settings”->“Apps” ->“VIEW ALL ×× APPS”->select the app you want to set->“App notifications” to take advantage of additional set up options.