Yes i thought so but i just ask in case there was another way of doing it, anyway many thanks for your assistance, very much appreciated.

Yes, you 're welcome, can i get you mark my answer as best to gain xp ?

OK in that case you only need to have one line for the attribute.
Go to product, at the tab variant, instead of have 3 value you just need to input like this "Window, Macos, Android" (which mean your produce only have one attribute and its value is "Window, Macos, Android")