When creating a new document in 4D Write, the page layout will automatically be set to the default setting. This means that each page will contain a header, a detail and a footer area. If the user chooses to work in the "Normal" view, the header and the footer area will be invisible. Most of the time, the user will not even know that the header and the footer areas exist.
If the user wants change the page setup for printing and the header and the footer options are not turned off, the user will not be able to change the top and the bottom margin to be lower than 20mm.
To remove the header and the footer area, select "Page" from the View menu to display the actual page layout. Go back to the View menu and deselect the "Header and Footer" option. The header and the footer area will then be removed.
Once the header and footer have been removed than you can go to the "Page Setup" and change the top and bottom margin as desired.