In general settings, the show history checkBox doesn't enable/disable log writing for chat.
seems to be messing the code
in file GeneralConfigurationPanel.java on line 294
(the change listener of showHistoryCheckBox doesn't apply change on ConfigurationManager)
and the config service string should be: impl.msghistory.IS_MESSAGE_HISTORY_ENABLED
in line 530 of ConfigurationManager.java, method setHistoryLoggingEnabled