如何更改这些代码，以便设置下载限制，并且没有人可以在添加产品方面更改它们？或者把它们藏起来，让别人看不见？

// Download Limit
woocommerce_wp_text_input( array( 
    \'id\' => \'_download_limit\', 
    \'label\' => __( \'Download Limit\', \'woocommerce\' ), 
    \'placeholder\' => __( \'Unlimited\', \'woocommerce\' ), 
    \'description\' => __( \'Leave blank for unlimited re-downloads.\', \'woocommerce\' ), 
    \'type\' => \'number\', 
    \'custom_attributes\' => array(
        \'step\'  => \'1\',
        \'min\'   => \'0\'
    ) 
));

// Expirey
woocommerce_wp_text_input( array( 
    \'id\' => \'_download_expiry\', 
    \'label\' => __( \'Download Expiry\', \'woocommerce\' ), 
    \'placeholder\' => __( \'Never\', \'woocommerce\' ), 
    \'description\' => __( \'Enter the number of days before a download link expires, or leave blank.\', \'woocommerce\' ), 
    \'type\' => \'number\', 
    \'custom_attributes\' => array(
        \'step\'  => \'1\',
        \'min\'   => \'0\'
    ) 
));

do_action( \'woocommerce_product_options_downloads\' );

echo \'</div>\';