How do I change logging level?

I want to get rid of clutter in logs (mailbox.log in particular). Supposedly the correct way to do this is to edit log4j properties .in file, so I did. I added loggers for soap and gal which generate the most noise and set them to WARN. I rebooted the server and made sure these settings were transferred to log4j properties file, but the log is still cluttered with useless soap and gal INFO entries. Is this not the way? I can't find anything on this in documentation.