why won't my 3D armor models work?

so, i've been trying to expiriment with armor. i made a waluigi hat for fun and tried adding it. can i get some help?
it shows up as a leather hat when i try to play with it and when i change the armor texture to the one i made on blockbench, it gets all screwed up. it's like it's completely ignoring the model. my model is a JSON model.