Had this same problem on the S4. Whenever I open the Google Music app, for example, and then turn up the volume using the volume rocker, that annoying warning that says "Listening at high volume can cause hearing damage..." or whatever pops up, and you have to hit OK to dismiss it. On the S5 that warning even seems to pop up more often. I never figured out how to disable it on my S4, which was running an older version of Android, nor do I know how to disable it on my S5 running Kit Kat 4.2.2. If anyone knows of a way, or if there is an app that defeats it, please let me know. Thanks.