Those who wish to change "the world" seldom do. "The world" as a cohesive entity doesn't exist: it is really, simply, Piles Of People.
In order to"fix" anything, you have a clear picture of the problem and create actionable steps to solve it. It is impossible to have a clear picture of any problems "the world" has, because "the world" is an incoherent abstraction. At best, you may attribute vague feelings to an abstraction.
The people who change the world are people who aren't trying to. They are people who are trying to build community in their neighborhood, or help a friend, or design refrigeration systems for third-world conditions. They are people who find a problem they can solve, and solve it.