i would definitely go back to a date before my sisters and parents had died. What would I change? Probably whatever would need changing to prolong those lives. (But that shouldn’t imply any lack of acceptance of Hashem’s plan. Just answering the question)
On a more “fun” note, I would like to go back to a time when life was more sincere and the yetzer hora had a bit less access and thank Gd for every second of it. Oh, that wasn’t fun either.
Okay, I would love to go back to a time when the chofetz chaim was still alive and people got married in their backyards and didn’t have to wear high heeled shoes. What would I change…