Currently, there is No WooCommerce built-in option to change number of products per row, so the products will always be displayed by the default value: 4 products per row.
In case you want to display different number of products per row than 4, there are a few options:
Option 1 (code change)
1. Login to your Admin Panel
2. Navigate to Left Menu -> Appearance -> Customize
3. Open functions.php
4. Insert the following code:
add_filter('loop_shop_columns', 'tishonator_woo_loop_columns', 999);
if (!function_exists('tishonator_woo_loop_columns')) {
function tishonator_woo_loop_columns() {
return 3;
}
}
5. Save changes
Option 2 (using a plugin)
We create a small plugin using the above code which adds a Customizer page with option to change that number.
The plugin is Free and it can be downloaded from WooCommerce.org: