What is the Best Option to Lighten Dark Underarms?

I'm african american and I have dark underarms. I've tried various at home remedies, but nothing seems to work. I've done scrubs,tried one type of skin bleach(didn't work at all) and other things. What would be a way to lighten them? I really hate the fact they are so much darker than the rest of me and I don't know why they are dark.