Hi Paul,
I am sorry. I believe this cannot be done in the current system. However, you can customize the code to achieved this. You can customize the code here: .../components/com_easydiscuss/themes/simplistic/categories.php .
I am really sorry, but we are actually quite tied up with our own internal development and we wouldn't be able to assist you with these customization right now ;( If this a priority, please do post them on our sales section at
https://crm.stackideas.com and our sales department would get back to you with a proper quote.
Please advise.