I want to change my software sources because I don't want to update my Ubuntu from other software sources. I tried to change it from Unity dock: I typed software source
and a icon appeared but when I clicked nothing happened.
And then I tried it from Update manager: I clicked on edit->source
but nothing happened.
I am still able to download and install updates as well as software from Ubuntu Software Center
You could give this terminal command a try:
Under GNOME/Unity
Under KDE
you can open your software from
here you will find your software sources
and you can chose your software sources you need every source has its description which is followed by #
you can delete the other software sources