Help:User preference option

User preference options (UPO) refer to settings in the files defaultsettings>Special:MyLanguage/Manual:DefaultSettings.php|DefaultSettings.php or localsettings>Special:MyLanguage/Manual:LocalSettings.php|LocalSettings.php that may be changed afterwards by a wiki user in his or her personal account settings on Special:Preferences, e. g. useremail>Special:MyLanguage/Manual:$wgEnableUserEmail|$wgEnableUserEmail or enotif>Special:MyLanguage/Manual:$wgEnotifUserTalk|$wgEnotifUserTalk.