Reduce snap sensitivity

Often Windows is snapping a window to be maximised when I don't want it to. Because I have multiple monitors, this seems to happen a lot. For example, I'm currently trying to spread a window to occupy all of two monitors. This is just about impossible. I have to turn snap off while I do it, then back on again (as I do use it often), otherwise it ends up maximising to one of the two monitors. Is there any way to make it less sensitive. I wasn't moving my mouse cursor right up to the edge of any screen, but it still snapped.

Uncheck...

Surely that's the opposite of what I want? Mine is on the default of unticked.