Hi.
Thank you for contacting us.
To make the "attach a resume" section mandatory for the candidate's resume submission form, please go to this file:
wp-content/themes/noo-jobmonster/layouts/resume/resume_general.php line 127
and change the source code from:
noo_file_upload_form_field( 'file_cv', jm_get_allowed_attach_file_types(), noo_get_post_meta( $resume_id, '_noo_file_cv' ), '' );
to:
noo_file_upload_form_field( 'file_cv', jm_get_allowed_attach_file_types(), noo_get_post_meta( $resume_id, '_noo_file_cv' ), false, 'required' );
Please use the child theme and copy your changes to the child theme folder to avoid issues when updating the theme.
Regards.