I want to go back in time to August 12th of this year because there were really dumb things that I did that had caused my suffering to happen, And if I had the power to rewind time to that particular date, I would not think about making those same mistakes that got me in this mess
If I could go back without making things worse, I would prevent the September 11 attacks from ever happening. But since things don't work that way, I wouldn't change anything because how do I know that by saving thousands from the terrorist attacks that day, I won't kill millions in the future. If I prevented the attacks, America wouldn't have gone looking for Osama bin Ladin and he may have had time to plan something much bigger. Even though I wish all those lives wouldn't have been taken that day and as much as I wish those people didn't have to go through that fear, it is a part of our history that seems impossible to erase.
While the main argument against this is that one could change something that would lead to unforeseen consequences, I see two ways around that.
First, assuming we can use this time travel more than once, we can change something, go forward in time, look for adverse effects, and if we see any, we can go back in time and correct the event.
Second, there are probably some actions that you could take that would not have negative effects, almost for sure. For instance, preventing the assassination of Lincoln. What bad could have come out of him living longer? It would've been advantageous for the country to have a stable Presidency during those turbulent times.
Changing something in history would change way too much. Things would never be any better than they are anyway for the simple fact that nothing can be perfect on this planet therefore terrible things would still happen. But then again, if i had to change something i would go back to the referendum for Crimea to join Russia and put a bullet in Putin's skull. Or two :3