WooCommerce Product Sorting

I would like to create more sorting options on my WooCommerce Shop page that allows the customer to view products by:

https://i.stack.imgur.com/SM4KH.jpg

As opposed to the default sorting:

https://i.stack.imgur.com/3J6Iz.jpg

In my functions.php file:

// Modify the product sorting.
    function custom_woocommerce_get_catalog_ordering_args( $args ) {
    	if (isset($_SESSION['orderby'])) {
    		switch ($_SESSION['orderby']) :
    		case 'price_asc' :
    		$args['orderby'] = 'meta_value_num';
    		$args['order'] = 'asc';
    		$args['meta_key'] = '';
    		break;

    		case 'price_desc' :
    		$args['orderby'] = 'meta_value_num';
    		$args['order'] = 'desc';
    		$args['meta_key'] = '_price';
    		break;

    		case 'popularity_asc' :
    		$args['orderby'] = 'rating';
    		$args['order'] = 'asc';
    		$args['meta_key'] = '';
    		break;

    		case 'popularity_desc' :
    		$args['orderby'] = 'rating';
    		$args['order'] = 'desc';
    		$args['meta_key'] = '';
    		break;

    		case 'sales_asc' :
    		$args['orderby'] = 'sales';
    		$args['order'] = 'asc';
    		$args['meta_key'] = '';
    		break;

    		case 'sales_desc' :
    		$args['orderby'] = 'sales';
    		$args['order'] = 'desc';
    		$args['meta_key'] = '';
    		break;

    		case 'date_asc' :
    		$args['orderby'] = 'date';
    		$args['order'] = 'asc';
    		$args['meta_key'] = '';
    		break;

    		case 'date_desc' :
    		$args['orderby'] = 'date';
    		$args['order'] = 'desc';
    		$args['meta_key'] = '';
    		break;

    		case 'title_asc' :
    		$args['orderby'] = 'title';
    		$args['order'] = 'asc';
    		$args['meta_key'] = '';
    		break;

    		case 'title_desc' :
    		$args['orderby'] = 'title';
    		$args['order'] = 'desc';
    		$args['meta_key'] = '';
    		break;			

    		endswitch;
    	}

    	return $args;
    }

    add_filter('woocommerce_get_catalog_ordering_args', 'custom_woocommerce_get_catalog_ordering_args');

    function custom_woocommerce_catalog_orderby( $sortby ) {
    	$sortby['price_asc'] = 'Price (Lowest to Highest)';
    	$sortby['price_desc'] = 'Price (Highest to Lowest)';
    	$sortby['popularity_asc'] = 'Popularity (Ranked Highest)';
    	$sortby['popularity_desc'] = 'Popularity (Ranked Lowest)';
    	$sortby['sales_asc'] = 'Sales (Highest to Lowest)';
    	$sortby['sales_desc'] = 'Sales (Lowest to Highest)';
    	$sortby['date_desc'] = 'Date (Newest to Oldest)';
    	$sortby['date_asc'] = 'Date (Oldest to Newest)';
    	$sortby['title_asc'] = 'Alphabetically (A-Z)';
    	$sortby['title_desc'] = 'Reverse-Alphabetically (Z-A)';

    	return $sortby;
    }	

    add_filter('woocommerce_catalog_orderby', 'custom_woocommerce_catalog_orderby');

As the WooCommerce support page (https://docs.woothemes.com/document/custom-sorting-options-ascdesc/) for this only has three examples on how to do this, I was wondering how would I be able to achieve the other settings for the desired effect, as some of the options I’ve placed in my functions.php file aren’t currently working and my sorting filter now looks like:

https://i.stack.imgur.com/Mp0lM.jpg

From one of the responses I received, I was told

modify the $sortby variable in your custom_woocommerce_catalog_orderby() function to make it look the way you want

and would kindly like some further clarification on this.

Thank you.