Submit page categories and subcategories

Hi all

On my site I’m using version 6.1.1 I have four parent categories, when a user try’s to add a new listing they can only choose from one of the parent categories and then a selection of subcategories drops down and they can choose one of them. I would like to give them the option to choose from any of the categories or subcategories like in the previous version is this possible or am i missing something

thank you

https://creativehealthireland.ie/submit/