i have the axiom 49, have had it for 2 weeks now, it'll prolly be another year till i figure out how to properly work this thing but it is so damn amazing. anyways, waht u need to do is press the Program and Bank LSB buttons at the same time. On the little blue screen, it'll bring up the velocity curve parameters. Use the plus and minus signs to change it.
anything with F means that its gonna be a Fixed velocity. Like no matter how hard u press the key, it'll always usually play at that set velocity.
anything C means that you'll be able to set it to whichever velocity you want.
Id recommedn downlaoding the axiom user guide, its really helpful.