You can override newmessage_form.php template (instruction in https://www.shamimsplugins.com/docs/front-end-pm-pro/customization-front-end-pm-pro/change-templates/ ) to change header OR use shortcode https://www.shamimsplugins.com/docs/front-end-pm/shortcode/fep_shortcode_new_message_form/ in any page/post from where any user can send message to admin (use “to” as admin nicename and “heading” as “Contact Admin” in this shortcode)