qtcam keep crashing when Color Space/Compression stay at MPEG

[HTLife]

The default setting of qtcam was fine the view the camera image correctly.
However, when I try to change the "Color Space/Compression" under Video Capture Settings from YUVU to MPEG, the program crash.

And because the program kept the setting, so even if I restart the qtcam and select the camera, it crash immediatly.

I tried to purge the program setting by sudo apt-get purge qtcam, but this didn't works.

How can I remove the config to default?