When you select print, a box should be displayed in Windows where you have to select which printer you want to use.
Highlight the printer, you should see a button just below or to the right of the printer list that says PREFERENCES, click this then another box should appear, in this select the Print/Quality tab (This may vary for different printers). Under this you should see the paper size being used … This should be A4 Portrait. You can check all the other tabs as well to ensure it is all A4 and 100% magnification/full size.
Dave