how can you change what you saw? What you change it to would be what you saw in the beginning, since what you saw is the future and when you look back you would still see the future. Its like the paradox of the past. You cant change the past, because the past has already existed. If you changed it to another past, a different you would exist, and you wouldnt have gone back and changed the past, but then you WOULD have gone back, but then you wouldnt...
The_One
PS by the way, you cannot see "versions of the future", thats only in movies. There is one future, defined as the outcome of the events of the present.