To test the campaign feature I changed the campaign vars in global.config.php, but did not remeber that when installing an update of Piwik, so I lost 2 month of campaign information. So please move those parameters into normal config, that is not automatically replaced when updating.
as stated in top of global.ini.php
; If you want to change some of these default values, the best practise is to override ; them in your configuration file in config/config.ini.php. If you directly edit this file, ; you risk losing your changes when you upgrade Piwik. ; For example if you override enable_browser_archiving_triggering, ; edit config/config.ini.php and add the following: ; [General] ; enable_browser_archiving_triggering = 0