Previously you could set all of you product image sizes in WooCommerce > Settings > Products > Display, but that entire section has been removed since WooCommerce version 3.3.
Image sizes can now be configured under the Customizer. Go to Appearance > Customize > WooCommerce > Product Images.
Also, note that image heights have intentionally been removed, as they are calculated automatically based on your settings and single, product image no longer has any crop settings; they will always show uncropped.
After making image size changes in the customizer, it can take a little while for images to regenerate the thumbnail sizes. You can get this quickly done with https://wordpress.org/plugins/regenerate-thumbnails/