Changing the order in which WooCommerce displays product categories to create a custom order.
To do this I navigated to the admin page Products > Categories.
On this categories page is shown a list of the various products order with child entries beneath their parent.
Viewing this page there is no textbox along the row to set the numeric order. Checking on the left for adding a new entry, likewise.
So how is the order of the category entries set?
On the Product category page to chagne the order of the entries simply drag the relevant item up or downto the positin you wish it to take.
Once an entry has been moved the little spinner will show whilst the updated order is being saved.
After the page has refreshed and the spinner has stopped the parent page has moved. And better still, all the child entries have been relocated too!