I was looking for the parameter which is handling the background so I opened the settings.cfg file, then the search module with CTRL+F and typed BACKGROUND, I was surprised that the search found nothing. I have eventually found it manually line 121 with this ortho :
G_USE_HIGH_QUALITY_ACKGROUND =
"ackground" should be correct "background" since most of users would instinctively search as me "back" in the module in order to find the parameter.