How to change the function of music lockscreen buttons on S5 mini?

[photohunter]

I have my S5 mini for just a few days and I was very pleased with the lockscreen while playing music. It has got the play/pause button and back and forward buttons. But recently, the function of these two has changed. Now it is used o adjust volume, When I press the back button, the volume goes on down, when I press the forward button, the volume goes on up. This is really annoying, because I can easily adjust the volume with the hardware volume buttons on my phone, and I would like to have the previous function back, so I can switch between songs without having to unlock my phone.
Any suggestions?

 

[George H Martin]

Use Google Play Music rather than Samsung's music player.

 

[photohunter]

Well, I am using Rocket Player and I just can't get enough of it. It is the best music player I've ever had and I just don't like Google Play Music or the native one. Is there a way to do it without Google Play Music?

 

[photohunter]

Guuuys, no help for me?