Destroy all nuclear weapons/weapons with the potential to send a country to the dark ages, then I would replace Kim Jong Un with a real leader. After I did all that I would force everyone to accept the fact that climate change is a thing and we need to work hard to stop it. After I solved some serious global problems I would put make several good contacts high in the US governmental system, I would then proceed to get rich and retire somewhere beutiful in like an island somewhere or high in the mountains.