I'm not in front of my controller but, I think if you change a value and hit apply, it will revert to whatever it was before. You have to change a value, hit ENTER, then hit apply. You can change as many values as you like before hitting apply but you MUST hit enter when you're done changing a value for it to stick.
I know for a fact that's true for most numerical settings. If that's not it exactly, it's something similar to that to get the value to stick before hitting apply. I kind of recall having the same issue a few years ago.