Thanks, yes found it now. I've gone into this record and I haven't found anywhere where I can specify the printing form. Theres the Custom Code tab where I have selected my script and the events I react to

Page init

,

Save record

,

Validate line

and

field changed

. Note AFAIK (I've inherited this script from someone else) the script functions are not doing anything related to selecting a printing form. The save record just checks that atleast 2 line items are selected/defined. The other functions dont do anything yet (empty functions).