Edit #2:
I actually found a much easier fix for my problem, then what I originally posted. I'm not sure if the original steps are needed for this to work, but try this first:
I had originally plugged my LifeCam into a USB 3.0 port. By reinserting it into a USB 2.0 port instead, everything works perfect. As far as I can see.
The following is my original post and first "Edit":
I know this is an old thread, and maybe this is old news, but I believe I just found a permanent solution for this problem.
I've just started tinkering around with streaming, and I admit being a n00b at that. But the problem with my Microsoft LifeCam in OBS annoyed me to the degree, where I couldn't stop before I had found a permanent solution, not just a quick fix.
What worked for me:
I'm on Windows 8.1
Locate your OBS program folder (mine was at "C:\Program Files\OBS").
Right-click the folder and choose "Properties". Remove the "Read only" or "Writing protection" on the folder and "Apply". Answer "Yes" when it prompts you about doing these changes to all of the sub-folders as well. You need administrative rights to do this.
Hope this works for you! I apologize if some of the wording is wrong, my Windows is in Norwegian, so I can only guess what it's called in the English version.
Edit #1: I was a bit to quick on the trigger there. Although it saves the new settings when you click "OK" on the "Device Selection" screen, it still resets back to the old "dark" settings when you stop the stream or preview. I'll do some more troubleshooting, and I will update this post if I find anymore solutions.