Revive Adserver's global settings are stored in a configuration file in the "var" directory of the installation. In order to be able to update global settings via the Revive Adserver UI, the web server user must have permissions to write to all configuration files in that directory (that is, all files ending in ".conf.php").

However, it is recommended that you do not leave these files as writable at all times, to avoid accidental changes to your system. Add write permissions when you wish to configure Revive Adserver's global settings, but then remove the permissions again once you have completed making your changes.