To set up the shop to display a different number of items per row, navigate to Appearance > Customize > WooCommerce > Product Catalog. This is what you should be looking for on your screen:
Shop — Change the No. of Items per Row
To set up the shop to display a different number of items per row, navigate to Appearance > Customize > WooCommerce > Product Catalog. This is what you should be looking for on your screen: