Probably do everything in my power to ensure the gaming landscape isn't as predatory in terms of having to pay for online access on consoles and seeing the Devil itself ( big red N ) go down in flames. Also, try to make console exclusives seen as something nobody is interested in anymore and are unwilling to purchase, more or less towards the 2010s rather than the 2000s, otherwise some of my favorite franchises wouldn't exist.

XboxLive? Find a way to fudge all the numbers to make it look like absolutely nobody was buying it!

GameCube? Find a way to ensure little to no 3rd party devs make anything for it by any means possible!

PSN? Keep that free like it was for PS3!

Would need to spend months, if not years, to figure out how to make all of that and ending console exclusives a thing, but a world without all that, IMO, would be a better world.

I'd write a list of future events and share it everywhere I can, editorializing of course to make sure them coming to volition validates my political views, and then use the eventual fame to shape the world in my image.

Ignoring that path, and with no political sway of my own ...

I've got nothing. I'd be like 5 years old and Australian. And overall Australia's doing pretty fine. If there's one issue I'd focus on it's digital privacy and my biggest adversary there would be Google. IDK, there's not really one domino I can affect to change things. Maybe warn about 9/11 and the subprime mortgage crisis but I'm pretty sure other people already did both of those to no avail. Plus I'd be 2 or so years old at the time of 9/11 so that'd probably not go well.

The other half of states that do not have ballot initiatives should have them. So the drug war would have ended peacefully. Contaminated overdoses and corruption would have been prevented.

Prohibit social media.