How can I create a drop down menu for categories?

Hi,

I want to have a top drop down menu to display all the category -> all sub categories . Right now I have 3 layers of categories, For instance:

Shop vanity online -> wall mounted type -> bamboo collection -> A configuration -> product 1/product 2....
-> B configuration-> product 1/product 2...
-> TSS collection -> A configuration
-> B configuration
The problem i have now is when I set "shop online vanity" as top menu item (I've set menu item type as "hikashop category listing"), but when i click on it, it goes to the page where display all the sub categories. No drop-down categories are showing under the menu.

Please advise, thanks a lot.

Best
Zoe