In this screen you can select the fields you want to use.
The task fields that you don't use won't be displayed in the task edit window.
They will also not be copy pasted when you try to paste in a text editor.
The columns displayed in the note and the task tables are independent from these settings.
In order to select the fields to display in the note or the task table, click on the button at the right of the note or the task table header.