Hello everybody, thanks for the new answers. I think I know now what it is (it was a mistake of mine).
How can I explain it?
I use my computer for five activities: general, learning, writing, webdesign and play. I have a desktop for every area. Often, when I install a program, I see the shortcut on every desktop, so I thought that Windows could access any program from any desktop (especially since everything is on the same hard drive).
That this is not the case, I noticed later (and yes, I feel very stupid because of it)
I apologize for the circumstances that I have made and thank you again for your help.
P.S. Since my English is rather modest, I used the Google translator. I apologize for any mistakes.