Submenus don't show

I’m trying to add submenu to a page which is on my main menu, but it doesn’t show.
Here is a link to my site:
https://www.blackseastars.com.au/

I want the [My Account] page to be accessed as a submenu of the [Shop] page.

I’ve tried making the [My Account] page to have a parent of [Shop]:
https://www.blackseastars.com.au/wp-content/uploads/2015/11/img1.png
When I do that, I can access https://www.blackseastars.com.au/shop/my-account/ but the [Shop] menu item doesn’t expand to show the [My Account] item.

I also tried re-arranging the menu structure in the Appearance/Manu page in the dashboard. That doesn’t seem to do anything
https://www.blackseastars.com.au/wp-content/uploads/2015/11/img2.png

What am I missing?
Thank you!