Well, "Charles Kenyon", thank you for your suggestion, still of all four word documents which were opened in my computer and visible in the Taskbar all vanished except one, probably the one which was used last. Then when I opened another already existing in my computer word document, it appeared on the desktop itself replacing the one left of the four which were already opened.

So,:
1. I am not happy with vanishing from the Taskbar of all, except one, the already opened in the computer, word documents; anyway, where were they when they vanished from the Taskbar; where should I look for them to draw them up to the desktop if necessary...? They should still be opened since I haven't shut them after all...

2. It's true, the other (fifth) just opened word document appeared on the desktop WITHOUT showing the other word document still seen in the Taskbar, however in the moment of having it opened, the one left of the four just mentioned, DISAPPEARED from the Taskbar and from the Desktop where only the one I've just opened from the file remained...

The point is I would NOT like to change anything regarding the already opened word documents; I would still like to have them visible in the Taskbar and NOT being replaced by another word document which I wish to open. The only thing I am keen to change is to prevent one of the already opened word documents from popping up on the Desktop together with the document I am opening in addition...

Still hopping there must be some way of fixing it.