it's been awhile since I made that change, but I believe if you go into includes/modules/pages/contact_us/header.php and look for this line:
Code:
zen_mail($send_to_name, $send_to_email, EMAIL_SUBJECT, $text_message, $name, $email_address, $html_msg,'contact_us');
the third item being passed with this function is where the email_subject comes from. currently, the code is set so that whatever subject the customer types will appear as the email subject. To have the NAME from the dropdown menu show up as the subject, change to:
Code:
zen_mail($send_to_name, $send_to_email, $send_to_name, $text_message, $name, $email_address, $html_msg,'contact_us');
as always, backup and test changes before using on live site..