Change perspective to shift into a parallel universe — altering past to change future
Realize that you do not change the world per se; you change your own personal perspective, which instantly shifts you to a new, slightly altered parallel universe. The only way to change the future of a timeline in physical reality is to concurrently change the past. When the change in the past occurs during a moment you decide you weren't present for to be able to tell the difference, the alteration can occur seamlessly. This happens almost all of the time.