orders.controller('OrdersCtrl', function ($scope, $http, $rootScope, $location, $notification, $routeParams) {

        // this works
        $scope.initGrid = function () {
              $scope.gridData = new kendo.data.ObservableArray([
                { artist: "Pink Floyd", track: "The dark side of the Moon" },
                { artist: "The Beatles", track: "I've just seen a face" },
                { artist: "Queen", track: "Innuendo" }
              ]);

              $scope.gridColumns = [
                { field: "artist", title: "Artist" },
                { field: "track", title: "Track" }
              ];

        };
        // this does not working
        $scope.update = function() {
                $scope.gridData[0].set("track", "Hey you");
        };

    });

<button kendo-button ng-click="update()">
  Update from code
</button>

TypeError: Cannot read property '0' of undefined