Making the stone soup changes the villagers by all the villagers gave something to the stone soup and learned how to trust each other again.
 In the story it says that the villagers did`nt trust each other. The monks knocked on many doors and no one answered, "These people do not know happiness" they all agreed. So, Seiw decided to make stone soup. 
Also, In the story, it says a little girl ran home and got her mother`s biggest pot. Then all the villagers started to give somethig to the soup. They gave onions, carrots, salt, pepper, and bread.
Lastly, In the story it says that after all the villagers gave somethig to the stone soup they all ate and started to trust each other again. They gave the monks a place to stay and thanked them for showing them happiness. In the morning, everyone gathered together near the willows to say farewell. Thank you for having us as your guests, you have been the most generous the monks said. Thank you with the gifts you have given, we will always have plenty.
This shows that at the begining of the story the villagers were suspicious of strangers and their nieghbors. But when the monks came along and tried to make the stone soup everyone learned to trust one another and gave the monks a place to stay.
This reminds me of when my brothers use to take my money and sneek it out my bank and I was suspicious  of them so I did not let them come in my room. Then my mother told me not to be so mean so I let them back in my room only if they would`nt take my things and they stopped. Just like when the villagers were suspicious of each other until the monks came along and made stone soup together.