problem saving video settings?

[darkinertia]

i just picked up this game recently and ive been trying to mess with the video settings to drop the textures and other settings down a bit but every time i put the slider down and press enter and then go to another tab and come back, it goes back up to the setting it was at. the only thing i seem to be able to change is windowed mode and the resolution but everything else wont change

does anyone know how to fix this?i got it on steam