Object Array Not Updated

controllers.application.js

import Ember from 'ember';
import {set} from '@ember/object';
import { A } from '@ember/array';
export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  apiObj: [
    { arr : A(['s'])},{ arr : A(['s'])},{ arr : A(['s'])}
  				],
  actions: {
  	change(obj,index) {
      let newObj = obj;
      // set(obj, 'arr', A(['x']));
     	newObj.arr.pushObject('g');
    }
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
<br>
<br>
{{#each apiObj as | obj index|}}
	<b {{action "change" obj index}}>{{obj.arr}}</b>

  {{#each obj.arr as |arr|}}
  
  "-{{arr}}"
  	
  {{/each}}
  <br>
{{/each}}

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "3.4.2"
  }
}