Yes, you need to save them into the DefaultEngine, or Default Scalability files.
The scalability is useful, as the commads sg.XXXXXX 1/2/3 are the ones that you will see in the scalability configs. You can then set different settings based on the different sg.xxxxx settings used.
[PostProcessQuality@0]
r.MotionBlurQuality=0
[PostProcessQuality@1]
r.MotionBlurQuality=1
So if you did ‘sg.PostProcessQuality 0’, you get no motion blur, but ‘sg.PostProcessQuality 1’ will give you motion blur 1. You can have other settings in each of these so that when you possibly add a graphics options page, you can simply use Low/Medium/High/Epic to relate to sg.xxxxxx 1/2/3/4 to the headers in here (0/1/2/3) and have different settings on or off based on the players graphics settings.