How to change iphone sound function?

Ok so this might be a new question but, when i lower my iphones 6 volume all the way down during the home screen it goes to mute, and if someone calls then its muted fine.
But when i go to a video its saves its last volume so it could be all the way up on the video but not the ring.
So is there a way you can control those volumes the same?
But there's also a 3rd volume setting and thats when your on the phone with someone and thats how loud the speaker is, so i would still want that function. Lol

There's two different 'volume settings' when you're on th home screen you can adjust 'sound effects' which is basically notification sounds and the ring tone volume. If you slide up control centre (slide from the bottom edge of the screen up) the volume setting there's the one for videos and games etc. So if you go into settings and then 'Sounds' you can adjust the volume of the Notification sounds and ringtone, then if you turn of 'Change with buttons' you won't be able to change it unless you slide the mute switch which will put the phone in silent as normal. Here's a pic on my iPad with iOS 9 (the setting is basically the same)