I’ve edited as suggested, but nothing changes. The code is now :
add_action( 'after_setup_theme','lh_move_secondary_navigation' );
function lh_move_secondary_navigation() {
if ( is_page( array( 4536, 4537, 36, 4538, 4534, 4535 ) ) ) {
remove_action( 'generate_after_header', 'generate_add_secondary_navigation_after_header', 7 );
add_action( 'generate_after_header', 'generate_add_secondary_navigation_after_header', 15 );
}
}