1- Render nukes/biological agents/poison gasses/(WMDs) & gunpowder/explosives inert. Then watch how long it takes for people to pick up swords & or
make new ways to kill each other.
2- Make everyone into true hermaphrodites, and make sure to make is so folks can give birth to one children (each) at the most. (With exceptions for
child mortality.)
3- Make a cure for cancer/diseases/illnesses/obesity etc that anyone could find growing like flowers, maybe a dandelion, some sort of pesty weed.
4- Clean up all the pollution, fix the environment and make it easy for food to grow.
5- Give everyone telepathy/empathy/teleportation/tk/pk ect. mindpowers though I'd let them not listen to people if they didn't want to, as some
people will complain about -anything-. Also I would make it so there was only one language, just so folks could talk about their problems.
6- Erase everyone's debt, then watch how long it takes for everyone to dig themselves a new debt hole.
7- Fix the VA

Which likely would need an act of god to fix.
8- Make it so that anyone who orders killings or kills for religious reasons/terrorism dies slowly, and in a very disgusting painful manner.
9- Make it so no natural/unnatural event could end the world. However, I would not muck with stopping natural disasters. If you want to live in
hurricane / tornado / flood zones /on the sides of volcanoes, it'd be on you to know when to take shelter or move to higher ground.
10- Make myself immortal and a shape shifter.
11- Make it possible for me to correct things at a later date if something got botched along the way.
12- Make absolutely sure everyone knew there was god(s), and that he/she/they gave a damn about them and the planet.
13- Then I'd go make Mars into a garden world, so folks had incentive to work out how to get there. Then do the same for a planet in a distant galaxy
for the same reasons.
14- Put all the information on all the conspiracies out where it could be examined, and then watch everyone make new ones.
15- After all of that, I'd probably go and enjoy myself doing stupid and silly stuff... because I could.
M.