I have found out.
Its easy.
1) Click on Open Qube Manager.
2) Right-click on the standalone qube/template that you would like to update.
Now the pc will look for updates on the web.
3) Follow the instructions in the window.
By pressing Y the updates will be downloaded and installed - the time for this is shown in the window.
By pressing ENTER after the installation the standalone qube gets shut down and then the standalone qube is updated and ready to use.