There are two steps to this:
1. Which columns?
DocuGen allows you to specify which columns from your board will appear in your document through the Settings > Table styling (or Subitems styling):
Go to your DocuGen view and click on the Settings tab at the top, then click on the Table styling sub-tab. You can select all columns or some columns.
Any changes to the settings are saved automatically.
DocuGen allows you almost unlimited styling options. Check out the Placeholders article for details.