I have example fixlets/tasks for setting client settings here: https://github.com/jgstew/bigfix-content/tree/master/fixlet/clientsettings
I also have a “Client Settings Manager” Console Dashboard that makes it easy to create the fixlets/tasks to set client settings: https://github.com/jgstew/bigfix-content/blob/master/dashboards/ClientSettingsManager.ojo
These can be adapted to set any setting and are the method I would recommend for setting client settings over any other method, though many methods are available. This option also has the benefit of working for all operating systems in the exact same way.
You can also edit the registry directly and restart the client service. (which is typically required when setting them this way, but not usually when using the method above) The settings are generally found here in the windows registry: HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\BigFix\EnterpriseClient\Settings\Client
This option only works for windows clients.