How Do I Fix This

Back in the day,Just about every Dart you would see, was dog-tracking. I mean, several of us guys in high-school had Darts or Novas, and in none of them, did the rears follow in the same tracks as the front.
The alignment guy centers the steering wheel to the Thrust angle, and the driver never even knows.
A lot of modern cars have rears that are adjustable, so the T-angle can usually be zero'd.