For years I have been using multiple monitors on my Windows desktop systems, as in the following photo for Windows 7, more than a decade ago, when I used four 1920x1080 (FHD) displays, all in landscape mode:
You have to configure multiple monitors so that Windows knows their relative positions (it has access to their resolutions via device properties of each display).
The animated GIF below shows how you carry out the relative positioning under Windows 10 (Windows 11 is similar, earlier versions of Windows looked slightly different).
These days I use larger 1920x1200 (WUXGA) monitors, with the rightmost monitor in portrait mode (better for long lists and tall documents):
You use the "Identify" button to show the device number that Windows has given to each monitor.
People seem to encounter trouble with using the mouse to drag-and-drop the rectangles during this relative positioning of displays, I can tell you that I did myself early on when I started using multiple monitors It can be a little tricky to get the relative positions to "sticK" (a web search like this reveals the annoyance that it has caused some people).
The key action, as demonstrated above, is to drag each rectangle right across the border of the adjoining rectangle and release the mouse button.
After that the rectangle that was being dragged springs back and leaves a small visual gap between the two rectangles. It seems that his gap causes people to keep trying to get the two rectangles to touch each other, but you just have to get used to the fact that this is not how it works.
The procedure often fails of you merely drag each rectangle near bit not right across the border of the adjacent rectangle.
I hope the above tip resolves this annoying issue for you.
