If the labels are printing out differently than they are showing in the Print Preview, the problem is usually caused by the settings in your printer driver. 

You'll want to open the "Devices and Printers" window and click on the printer, find the "Advanced" tab, and make sure that the correct "paper size" is selected to match the size of the labels that you're using. 

If that setting is already correct, there may be a bad margin setting, which I think would also be available through that "Advanced" tab or somewhere nearby.