Hi Thibaut
Have you created a Desktop shortcut for the old programs, and then right click the icon and choose Properties, then choose the Compatibility tab?
For some unknown reason the available previous versions of Windows in the drop down is dependent on the program itself, you will get different options depending on the program
Try doing the above with a few icons on your Desktop and you should see, some will have different options, this must have something to do with the application programming, rather than a setting in Windows 10
For example see below for one application on my Desktop,yet many others only show back to Windows 7 or Vista . .
.