The way the middle table (sales or purchase etc) table works, is that there is a bookmark in the template telling the software where to insert the table

The table will be the sale items, purchase item etc depending on the form you’re in, and you’re also able to add ‘remove.XXX’ fields to the document (anywhere) to tell it to remove columns from this table  

There is no way at the moment to edit this middle table to change fonts colors etc.