First off, invest and diversify it in companies and startups also focused on positive change, like those creating technology for lowering the cost of food and necessities and improving lives of people with disabilities. Stuff that improves our everyday lives and creates real value in the world. Solving all the world's problems is not really something that one person can reasonably do on their own effectively, so it needs to be allocated to other groups of people where it can make a proper difference. Build housing and invest in education globally with the proceeds, helping those in need to get back on their feet. Investing it intelligently means you'll never run out of cash, and even have more year-over-year to improve the lives of more and more people. If there are a lot fewer people struggling in the world, those people can then dedicate time to solving world problems and improving lives and continue the cycle.

As you acquire more money you can provide more services to more people, make more positive investments and help and improve the lives of more people.

Shit, I think I just described capitalism. Whoops, nevermind. Sorry I know that sort of thing is frowned upon here. I think the best thing to do would be to give every person on earth $12 one-time. Well, minus the costs and logistics involved in doing that, so every person on earth can get $8 after expenses. That should do it.