Hi,
Generally, you can customize the position of our “related categories” section relatively to the “related products” section with our “Position Options” settings (in “WooCommerce > Settings > Related Categories > Single > Position Options”). For example, if you set the “Position” to “After single product summary”, and “Position order (i.e. priority)” to 19, then it will be displayed before the “related products” section. On the other hand, if you set the “Position order (i.e. priority)” to 21, then it will be displayed after the “related products” section. However, your theme may be using a non-standard position for the “related products” section, so if the above won’t work, please let me know which theme you are using and I will take a look into it.