- You'll find all the default settings (what to log, where to log, how to log, ...) at "Options" (Alt-O) > "IRC" > "Logging" (These settings are explained in the helpfile: /help Logging).
- You can override the default setting and disable/enable logging for a particular channel/query by right-clicking the channel/query in switchbar/treebar > "Logging" (A left-click on the window's icon at it's titlebar should open the same menu).
- You can browse your logs at "Tools" > "Log Files".