the class menu option doesn't seem to have a skill selection option and neither does the background menu option and there is no 'skills' menu option on the new interface on the left.
I’m trying to remember exactly how this worked from my own chance to play the newer build. IIRC the default skills appeared in the middle of one of the tabs and there was some sort of option/button to pop up a window change them from there, rather than a separate tab. Don’t quote me on that, though.