Apply the same manipulation as in the post for Debian/Ubuntu/Mint systems below:
https://www.justconsum.com/forum/index.php/topic,10.0.html (https://www.justconsum.com/forum/index.php/topic,10.0.html)
But instead of unlocking "Evince" as PDF reader software on the operating systems in the post, you'll probably have to unlock "Okular" instead if you use KDE for example.
Have a nice day :)