you may try to de-register/unset default post type and register post type with your requirements.
if ( ! function_exists( 'unset_default_post' ) ) :
function unset_default_post( ) {
global $wp_post_types;
$post_type="post";
if ( isset( $wp_post_types[ $post_type ] ) ) {
unset( $wp_post_types[ $post_type ] );
return true;
}
return false;
}
endif;