I did a clean install of the latest DokuWiki, installed this plugin and used:
sudo chgrp -R www-data *
sudo chmod -R g+w *
on the root of the website. Afterwards, I run the installer, log in, go to Admin and Configuration Manager and disable the Header Navigation. I click save and get "Settings updated successfully." However, The Show Header Navigation is checked again. I can not uncheck any of the options of prsnl10.