Domain-based (gpmc.msc) audit settings are stored in an audit.csv file in SYSVOL in the corresponding GPO folder
{XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}\Machine\Microsoft\Windows NT\Audit\audit.csv
This .csv file is then copied to below location (upon gpupdate /force), which applies the audit settings to the machine
%systemroot%\security\audit\audit.csv
Important: Advanced Auditing will not work at all if the "Default Domain Policy" is missing its audit.csv file in the SYSVOL folder
{31B2F340-016D-11D2-945F-00C04FB984F9}\MACHINE\Microsoft\Windows NT\Audit
Even policies set locally via secpol.msc won't work!
To restore the audit.csv file, simply edit the Default Domain Policy and set any advanced audit setting. This recreates the audit.csv file in the SYSVOL path and you can immediately revert the change to the Default Domain Policy.
Further information
The Security Setting Audit: Force audit policy subcategory settings (Windows Vista or later) to override audit policy category settings does not have to set by GPO since its enabled by default in secpol.msc on a clean OS.
auditpol /clear
You can clear all configured options on a computer via this command. This does not remove the audit.csv file from C:\Windows\security\audit but auditing will be disabled, which you can check with auditpol /get /category:*
Upon next gpupdate /force (in case of a domain-based policy), auditing will be turned back on
Locations
Local Security Policy (gpedit.msc)
stores its audit settings in
%systemroot%\system32\grouppolicy\machine\microsoft\windows nt\audit\audit.csv
this .csv file is then copied to below location (upon reboot or every 16 hours), which applies the audit settings to the machine
%systemroot%\security\audit\audit.csv
Domain-based (gpmc.msc)
audit settings are stored in an audit.csv file in SYSVOL in the corresponding GPO folder
{XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}\Machine\Microsoft\Windows NT\Audit\audit.csv
this .csv file is then copied to below location (upon gpupdate /force), which applies the audit settings to the machine
%systemroot%\security\audit\audit.csv