When working with multiple monitors you may come across this problem
You start an application and part of it is off the screen. Not a problem if you can get to the applications top window bar and move it back to where you want it.
What you do is right-click on the item in the taskbar and click on Move on the context menu. After this, press the arrow keys (I usually press the down arrow key but any of them will work), then move your mouse. You will find that the shadow box of the window in question is now being “dragged” by your mouse. Place it where you want on your screen by moving the mouse and then clicking the left mouse button. It will then stay there from now on.