Show us a screenshot please, and help will arrive.
If I understand you correctly:
Are you printing from the layout your're entering data on? If so, it's usually best to make a printing layout based on the classic theme.
This is the solution.
Thanks for your support.
You an also print from a themed layout if you select each part label (Header, Body, Footer...) and then select the white fill color for it instead of the theme specified color.