There are not camber adjustments in the rear (stock). -1.9deg rear makes me think you have suspension damage (or at least severe wear?) You WILL get dynamic negative camber, so maybe the rear is sagging hard? Did you have lots of weight back there?
You could probably fix it with aftermarket camber bolts, but you might want to find out why there is so much negative camber first.
Only toe is adjustable in the rear with stock parts.