- Select the nets for which you want to assign certain net class. (EDIT: use the normal means used in all systems and programs, Ctrl+click or Shift+click.)
- Select the new net class from the “New net class” dropdown menu.
- Click “Assign to Selected Nets” button.
- Close the dialog with OK.
The filter is only an optional way to reduce the amount of nets in the list from which you can choose. You can also assign the new net class to all visible nets. It’s logical when you think about the UI texts for a while and find out how it works, but on the whole it’s quite complex. Often I forget the step 3, close the dialog and am angry because it doesn’t do what I want, seeing that the new wanted values aren’t used when I continue routing. Then I open the dialog again, do it again and remember that I forgot something. We must be patient.