I select marker with content "new marker ".  Using event

$scope.onShow = function (e) {
         $scope.selectMarker = e.sender.marker;
         $scope.markerText = e.sender.marker.options.tooltip.content;
}

then I updated markerText to "Update marker" and click  to update

$scope.onUpdateMarker = function () {
                if ($scope.selectMarker) {
                    $scope.selectMarker.options.tooltip.content = $scope.markerText;
                    $scope.selectMarker.tooltip.options.content = $scope.markerText;
            }
};

On the map I see old marker content "new marker ".  How change content on map ?

Hello,

If I understand correctly, you'd like to change the tooltip content after showing the marker.
This is possible by calling the refresh() method on the tooltip after setting its content:
$scope.selectMarker.tooltip.options.content = $scope.markerText;
$scope.selectMarker.tooltip.refresh();

-- Live demo --

I hope this helps.

Regards,
T. Tsonev
Telerik

Thank you. It's work.