It allows you to change the ring tones/alerts for your current sound profile. So if you want to change how your phone behaves while in vibrate mode, set your phone to the vibrate profile and then go to "Set Ring Tones/Alerts" to set the options. You can do the same with all of the profiles this way.
Basically you made the wrong assumption about not being able to did the preset sound profiles. The set rings/alerts is what actually allows you to change those profiles.
Good question� I'm still kind of a newb at this too and didn't know that set rings/alerts changed the current profile I thought it just changed the normal profile
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