To move a window means to drag it across the desktop screen using the Mouse Drag technique described below. Only a non-maximized (custom sized) window can be dragged. In this example the window I want moving, the Notepad window, is at the back of the Microsoft Edge window; therefore the first thing I need to do is bring the Notepad window to the front by clicking on its Title Bar.
Fig 1.0 - Click on the Title Bar of a window to bring that window to the front of all other windows
Fig 1.1 - With the left mouse button still held down, on the Title Bar, move (drag) the window to a new position.
When you have brought a window to the front of all other windows the next thing to do is move (drag) that window into its new position. So click on its Title Bar again but this time keep the left mouse button (click) held down as you then move (drag) the mouse pointer leftwards/rightwards and/or downwards/upwards. Doing this will move the mouse pointer and the window. Once you are happy with the new position of the window release the left mouse button.
In this example I moved (dragged) the mouse pointer leftwards and then downwards, with the left mouse button still held down, until the Notepad window was underneath the Mcrosoft Edge window. I then released the left mouse button.
Fig 1.2 - When you are happy with the new window position release the left mouse button
Although the drag technique is straight forward, it does take practice to do the more skilled positioning. The drag technique is used in many areas of Windows 10, such as dragging a window, desktop icons and picture files. Practise does make perfect!
One thing to note is that a window can only be dragged (moved) when it is not maximized simply because it can only be dragged (moved) within the boundaries (display area) of the desktop screen. Therefore, it is impossible to drag (move) a maximized window around simply because it is already taking up the whole of the desktop screen's display area.