Why is it that on most new dvd’s which I buy and
try to back up. The dvdfab software want’s a dual layer
disc for the back up?
That depends whether your using the free version which has no compression functionality, or the paid version which does.
If your talking the paid version then look at the bottom of the UI and make sure DVD-5 is selected in the drop down next to the word ‘Quality’, if DVD-9 is selected you can change the default back to DVD-5 in common settings.