Unplug your monitor and place it on another PC, a friend's or spare PC. How does the display appear there. If it's improper or similar to the problems you have, then the monitor itself is faulty or mis-adjusted. Following the same instructions in prior posts and it works well in the test PC, then some setting is amiss or the video source is wonky. I can't find anything that will cause your issue unless monitor based as in h/w. Whether it is the monitor or video card that's a fault is still needs to be found. Since, you've stated you've done all posted, it appears as coming from h/w. The fault appears at the time of your husband's use may not be related to some improper right-click action, but bad luck at least it appears so. Thus, the action to test the monitor elsewhere.
Details, they matter. I have no clue in the monitor being used, OS, video card or source and PC based on.