How would you change the world?

I'd fix all the problems we've caused our mother planet to return it to the pristine condition that our race has failed to keep it in.

An even better approach would be to end the human race, because as I see it right now, the Earth is going downhill due to humans.
If the Earth goes downhill, everything loses (lose-lose situation). The Earth dies, we die, all life dies. <------- Not ideal.
However if we are gone, the Earth will be able to recover and at least it and all the other species won't face our fate.