post listed randomly?

hi,

I’m trying to get posts to list randomly on only one top level category page…

I have a category called portfolio, and this has plenty of sub categories which all use the same category-4.php template file (by using the Elevate Parent Category plugin (https://pluginscatalog.com/plugins/elevate-parent-category-template.html)

now, when viewing the main portfolio page (NOT burrowing down any deeper in the hierarchy) i want the posts displayed in a random order…

i can’t use code such as:

<?php $news = new WP_Query(“cat=4&orderby=rand”); ?>

as this will just display a random load of portfolio posts from all sub sections even when i am IN a sub section (it does however give me the correct effect when i’m on the top level portfolio page)

so basically i need code that will: (in english)

if the category is 4, display the posts from all portfolio subsections in a random order, if not (i.e. you’re in a subsection) display as normal using a standard loop.

I hope this makes sense? help would be much appreciated…