They have changed the commandments both in their form and, even more so, in their content.
At the beginning, there were lots of commandments, and they all had to do with animals being equal and with animals not acting like human beings.
Now there are no more commandments about not acting like humans. They have all been broken by the pigs and have been erased.
Now, there is only one commandment. It is still about equality, but it no longer has the same message that the commandments used to have. Now, the only commandment is that "All animals are equal, but some animals are more equal than others."