When creating a label in the single label interface, you have the option of previewing the label prior to purchasing it.  

Clicking the Preview button (Step 3) will open a new window. You should be able to review the label, verify that everything is correct and then close the preview by clicking the red X in the upper right corner of the pop-up box or the Close button at the bottom of the preview window.

If you do not see the red X, chances are you need to change your screen resolution settings. We recommend your resolution be no less than 1080.  This is standard for most screen settings.