AutoText can be stored only in a template. Documents cannot store AT. That said, documents can store inserted Autotext (the stuff showing in the document).
Automated Boilerplate Using Microsoft Word

The AutoText List field is not compatible with protection for filling in forms when used in a protected section. A traditional drop-down field would work (but is nowhere as flexible as the ATList field).

An IF field in the protected portion that tests for the results of a drop-down and inserts text works if the drop-down has calculate on exit checked in its properties.