Samsung Galaxy S5 — lollipop notification button

Hi all, my first post. Feeling somewhat frustrated with the lack of mute option but the alternative option seems to be to tap the volume button and get up the three notification options, but it doesn't on my S5 I just get the standard slider control and the settings cog. Even if I go into the settings option the customising options are unavailable. Am I missing some kind of activation option or is there a problem accessing this on my phone. All the YouTube clips I have seen demonstrating this option have been on other phones. Anyone else have this problem ?