The future is not something definite unlike the past. The future has many possibilties and those possibilities are affected by the decisions you make in your daily life. It is up to you. The past does not have possibilities because there is nothing elsethere to influence it. Even if you were to influence the past, you would be influencing the future instead seeing how the past has yet to happen.
Besides.... The future cannot "change" if it has not happened yet. You make the future with your actions and choices.
The future is alterable relative to how you decide to live it, the universe is infinite, you have an innumerable amount of choices you could possibly choose. You can do what you wish, you lead your future. You can alter the future by choices in the present. Blessed be!