This refers to the display of the columns in the edit screens, not on the PDF. 

Across all the modules you can show and hide the fields or columns. You can also rename some of them.

The examples here are for the Quotations module, but the same applies to the other modules.

Showing/Hiding Columns

To show or hide columns:

• Select the Cog
• Select Quotation Settings
• Select Show/Hide Line Item Columns

For each column there are three settings in the dropdown boxes:

• Show - Always visible
• Hide - Hidden on the screen initially but is shown when the user clicks on the 'Show more settings' link on the edit screen
• Remove - Not visible and the user cannot see them with the 'Show more settings' link

To change this, in quotation settings select 'Show/Hide Line Items Columns':

Renaming Columns

You can change columns names, for example,  ‘List Price’ to ‘MRP’, ‘Sales Price’ to ‘Final Price’ or ‘Multiplier1’ to ‘Hire Weeks’, etc.

• To do this:
  Select the Cog
  Click on ‘Quotation Settings’ (or another module's settings)
  Select ‘Customize Line Item Labels’
  Set the new names: