What would be one small detail that, if changed, might change the outcome of of the story?

In the book If I Stay, if I could change one small detail, I would make the whole family stay at the house. That way if the family doesn't leave the house, they would not get into the crash that they got into. If they didn't get into the crash Mia's parents would not die, and everything would be alright. They would continue to live out their normal everyday lives.