the image presented on the settings page is misleading.
it seems to be self aware enough to know the orientation of monitor the window is on, because it will change when you move the window from one monitor to another.
but the problem is the edges and corners show are not separate for each monitor and when selecting an upper left corner (say), the setting will only apply to the upper left corner of ONE of the two monitors (the one most upper and left).
what should be shown in that image is the entire virtual desktop like you see in the pager.