The way I kinda see it... we have 3 dimensions.
The present, the future, the past.
Even if we went back to past and did something or prevented something, it would stay in that past dimension. Your future would still stay the same, but the past dimension would be altered. Same with the future. I know that might contradict the widely accepted belief that if you change something in the past, it will affect future, however we don't know exactly what would happen since we don't have a time machine and we'll always stay in wonder until we can.