Liquid domain settings won't update

I make a quick liquid and it runs fine. If I change just the size of the source cube the simulation still runs but with no changes. I only get the changes to apply if I tweak the domain resolution. This is true for virtually any change at all, I always have to tweak the resolution. I can animate the source cube and it works ok, but if I try to manually move the cube during animation it just all disappears. Pretty inconvenient!