If you open up your "Profiles" option and scroll down to advanced it will allow you to either edit your existing profiles or create a new one. Then on a per-application/instance basis (E.G. phone, email1, email2, IM+, etc) it will allow you to set your volume settings.

You would want to change phone's out of holster and in holster action from "Vibrate+Tone" to "Tone" and set volume to "High". Also some ringtones are just low sounding in general. (For example on my device I have a Tune_BachFugueDMinor.mid that is barely audible unless I am in my home.)