Go to "Client" -> "Administration" -> "System settings" -> "eTouch" -> "Define eTouch menu", and in there select the checkbox for "Machinelist". Here there is more information about how that menu works. Once that is done the "Machine list" will be visible in the main menu of eTouch.
In eTouch main menu click on the "Machine list" short cut, and the form seen below will appear. It is here that you will be able to change the active machine in eTouch. Scroll up/down in the list and confirm your choice with "Save", or click on "Abort" to return to the menu for "Production order".