If you use WooCommerce 3.3.x and higher then use WordPress Customizer (it’s a feature in the WordPress admin) to change the catalog and single product Image settings.
Go to Appearance > Customize > WooCommerce > Product Images. https://woocommerce.wordpress.com/2017/12/11/wc-3-3-image-size-improvements/
After these changes, you need to Regenerate Thumbnails to apply them. You can use Regenerate thumbnails plugin to do this.