The selections you make here will be used, by default, on new sales that you create for this customer. You can override these selections when recording a sale.
If you want to learn about each option, hover your mouse over the field to display the field help (you'll need field help turned on, go to Help > Show Field Help).
If the Printed Form and Invoice Delivery fields are not shown, make sure the Sale Layout field isn't set to No Default or Miscellaneous.