Display sub categories on my shop/product page

Hello,

I have a webshop and I have set up my brands as parent categories and then the sub-categories are the collections.

When entering my shop/product page, I want to display all my collections (sub categories) and not the parent categories.

I have gone to Woocommerce settings>>products>> show sub-categories.. but all it does is to display the parent category..

Is there a way to only show the sub categories in my shop landing page?

//Emelie