I have the same issue, and every time I watch a new video, the settings will be changed to some other settings.
I have to click on the button "default setting" for each video in DeoVR.com.
Seems the "default setting" is not really default, just a setting holder.
However, we actually need 3 of such setting holders: 1 for VR180 and VR360, 1 for 3D flat, and 1 for videos and pictures in portrait mode.