Everyone in their life at least once have thought about changing the world to make it better place.
I think that one person can't change the world. Everyone have their role in that deed. Everyone should do something. People love being a human and living on the Earth, and have no time to think about the world around them. They do not notice that this world needs changes.
For example should do kindness as much as they can. Should help old people...
Make fun ideas that will force people to the in the right way. People should understand that they can live, not only survive. They should enjoy their life.
People should pay more attention on plants: plant trees, water the flowers and remove garbage from nature.
If people do the job they really like, working will be enjoyable. And there won't be so much criminals, that don't want to work. I think that the role of teacher is very huge in that question. Teacher should teach well. Every child has it's own interests, and needs unique approach.
Problems that we face these days seem to be endless. And if every person do some improvements, there will be lots of changes.