Plug in X to PC, wait until "USB connection" shows in pull down menu on home page (IGNORE the "Connection Detected" message). Touch "USB connection" and Lo!! The menu to change how the SD card operates.
Android apps are installed on the internal memory and there is nothing you can do against it. This is part of the security concept If you put apps on the SD card, this security concept is broken. That is why you have no choice. The described concept is only a part of the entire security concept, but it is the one responsible for not being able to install apps outside the internal memory.