javascript - Syncing data between model instances in Angular -

i'm angular newb. i've followed tutorial http://www.bradoncode.com/tutorials/learn-mean-stack-tutorial/ , have modified things (i have items instead of categories). i've created mean app, 2 models, users , items. add property items model called "owner" stores username of user created model. isn't hard, problem arises if user changes username - "owner" property doesn't change in item model instances created user. gather there ways of syncing data between views/models/controllers, how sync data between different model instances of different models. appreciated, thanks.

here item.client.controller.js

'use strict';  // items controller angular.module('items').controller('itemscontroller', ['$scope','$stateparams', '$location', 'authentication', 'items', function($scope, $stateparams, $location, authentication, items) {     $scope.authentication = authentication;     $scope.currentpage = 1;     $scope.pagesize = 10;     $scope.offset = 0;     // page changed handler    $scope.pagechanged = function() {         $scope.offset = ($scope.currentpage - 1) * $scope.pagesize;    };      // create new item     $scope.create = function() {         // create new item object         var item = new items ({             name: this.name,             description: this.description,             owner: $scope.authentication.user.username         }); 

here items.client.services.js 'use strict';

//items service used communicate items rest endpoints angular.module('items').factory('items', ['$resource', function($resource) {     return $resource('items/:itemid', { itemid: '@_id'     }, {         update: {             method: 'put'         }     });     } ]); 

and users.client.services.js

'use strict';  // users service used communicating users rest endpoint angular.module('users').factory('users', ['$resource', function($resource) {     return $resource('users', {}, {         update: {             method: 'put'         }     });    } ]);