Hi Daanoz,
The first thank you for used our product. If you want to custom any think of the Kunena template and don't lost style when you update new version of the template, you should add your custom to the current Joomla template. Example if you want to change the text color of the Kunena template, please open the template.css file of the Joomla template and add bellow CSS code section to bottom of file.
Code:
#Kunena table.blocktable {
color: #fff; /* You can replace the color code by your color code */
}
After that you save file and refresh you site. Let's us know if you have an other problem.
Best regards,
