I tried to change error_reporting in my Joomla installation, and no matter what setting I used, it always was stayed at value 69. It took me a few hours to find out what caused it.
I found out that in many places in jDownload, the error_reporting is set. Especially, when the system plugin is switched on, the error_reporting is set with each page view.
My suggestion is that you use error_reporting just when necessary and not set it as a default, especially in the system plugin