That's not what we've been doing with the lens - it moves around the screen. Maybe this is why we are having so much trouble with it.
That's strange - it should only move around if you move the mouse. If I leave the mouse in the same place, the magnifier (say) mid screen and scroll the wheel or use, say, 2 finger scroll on my touchpad, the magnifier doesn't move but the window below scrolls.

An interesting (?) trick is to click the scroll wheel, then move the mouse point below or above the marker placed on the screen- autoscroll at various speeds.

I don't know how to get the magnifier as a vertical strip.