I'd do several things:

• End colonialism before it started
• Make India a superpower
• Remove corruption
• Add a few more moons around the earth(looks good you know :D )
• There would be no terrorism
• There wouldn't be any nuclear warheads, nuclear energy will only be used to generate electricity
• Enabled Tesla to have built his free energy machine
• Everyone will have the same religion, caste, race
• And a lot more things that I could think of.