In recent versions there are three different volume sliders. I'd call them: "Notifications", "Alarms", and "Media". You have to check all three of these to be

In recent versions there are three different volume sliders. I'd call them: "Notifications", "Alarms", and "Media". You have to check all three of these to be sure. I have mine set to only "Alarms" and occasionnally allow "Media" when listening to music or podcasts, but after listening you have to reset "Media" to zero. (I don't have any kind of notifications alerts, sound or vibration)