Samsung really screwed the pooch on the volume control in the music app. I really like the stock music app as it does everything I want fairly well except for control the volume properly.
First, every time you plug in an Aux cable or headphones the volume goes back to 9. And then when you want to raise the volume, I keep getting a warning about how loud volumes can damage your hearing. Really?? So Samsung is now playing nanny police. Very annoying. And then the last problem is the "Smart Volume" control so all tracks play equally loud...nothing "smart" about it. It kind of works but every time I start the music app, I have to re-engage the feature. It never stays on. If you touch the volume, it also turns off. Very poorly implemented.
It really seems to me that this volume control issue (as well as many other screwed up features) are indicative of a company that doesn't understand how customers use their phone and doesn't really know how (or doesn't want) to make the software customize-able so options/features can be on or off.