Do I have the power to change things on a large scale? Cuz like, I was already an adult by 2011, and I still just sorta watched as shit went to shit. I did 'my part', and I warned people when I could about alarming trends they were unwittingly contributing to, but no one cared, and to be honest, unless one can actually hit the powerful folks, there is very little an individual can do.

If I have power to change things, to actually affect the powerful people, then I'm going to Y2K and I have a few ideas:

• Stomp Jair Bolsonaro to death a full decade before he becomes popular. When he was a nobody state representative from São Paulo who was only there to generate more seats for his party.
• Arrange a convenient accident for Steve Jobs years before the iPod drops. People talk about technology becoming boring, I place the blame for that entirely at Apple's feet. And it all began with the iPod, which in turn, if you believe the stories told, was Jobs' baby, to the point he harrassed the engineers at Apple for years until it was EXACTLY as he had planned.
• Stop 9/11 from happening, which slows down the US's descent into being a Police State, which in turn slows down the rise of neoconservatism/neofascism pretty much everywhere. Oh it'll still happen, but maybe if it happens more slowly, there might be fewer victims and people might do something about it sooner.

Oh and

• "Disappear" Peter Thiel. People really sleep on how much damage Thiel has done because he doesn't post cringe as often as say, Musk. But he's the high priest for the techbro "we are building god" faith.

I can't exactly do much about Climate Change with the time given. For that I'd need the same power-scale but to go back to the 60s, when the first scientists took notice of the trend but had their research suppressed by big oil.