I must be missing something obvious. This is not new.

Default Picking slip is denoted in OE Company Profile.

The User Preferences "Remember form settings" is checked.

The Customer record on the Invoicing Tab has the Picking Slip they use in their record selected.

Yet each time we post an order and go to print the picking slip we always have to pick out the specification as shown in the attached picture - yes I figured it out on how to attach a file!!