woocommerce_default_catalog_orderby options code example

Example: woocommerce_default_catalog_orderby desc

/**
 * This code should be added to functions.php of your theme
 **/

add_filter('woocommerce_default_catalog_orderby', 'custom_default_catalog_orderby');

function custom_default_catalog_orderby() {
     return 'date'; // Can also use title and price
}