I load up the game, open the video options menu, and a lot of the settings are quite low (like Actor Fade, Object Fade, Grass Fade, etc). I crank them up, and I can see the changes in-game perfectly well. But when I close the game and reload it again, the video settings have all reverted to their original low quality state.

I've even tried deleting the Oblivion.ini and default.ini, and having Steam regenerate them by verifying the game cache. That triggers Oblivion to redetect my video card, and I have to reset my resolution to 1920x1080, re-enable distant trees etc. Still no luck. Video settings stuck at low.

Anyone know what could be causing that? Is there any way I can manually change those settings in my ini file and set it to read only?

Is the game installed in Program Files or Program Files (X86)?

Also, when in game, use this console command, saveini and see if that makes the changes stick.