The code works fine on all our test websites. Please send the admin login details to infogvectors.com email address. I'll ask the developers to check the issue for you 

https://test.iotadaily.net/big-capabilities-test/

Thank you for your fast response. 

I inserted the above code into the Plugin "Code Snippets" (see screenshot). All caches of litespeed and wpdiscuz have been cleaned, but it still isn't working. 

Do you have any other suggestion?

Also switching it to "run everywhere" doesn't change anything.

Use the following hook code:

add_filter("wpdiscuz_author_link_attributes", function ($attrs) {
    $attrs = "_self";
    return $attrs;
});

Put the code in the WordPress active theme functions.php file.

This article should be helpful for you:  https://www.wpbeginner.com/plugins/how-to-easily-add-custom-code-in-wordpress-without-breaking-your-site/

Please delete all kinds of caches and check again. 

wpDiscuz also has a built-in caches system Please delete this cache as well. It's located in the Dashboard > wpDiscuz > Settings > General Settings tab. 

I've the "Enable Profiles URL" option activated so users can click on an author's comment and then get linked to his authors page. It always opens a new tab. How to make it just to work like a normal link without opening a new tab? 

Looking forward to your response!