When I open my Waypoint application on my iPhone, it shows my Reach spartan, Inheritor rank, 100 BPR, and my Reach Service Record.
How do I change it so that my new Halo 4 Spartan, rank, Service Record, etc… shows up instead of my Reach stats?
You can’t, the Halo Waypoint application hasn’t been updated to support Halo 4.
You’ll have to visit http://app.halowaypoint.com/ on your phones browser to access your stats for now.