I believe one person can change the world in more ways than one. Take an inventor, Jesus Christ, Hitler and other's. They made a huge impact on the world. Then I look at other's who tout funny things of this and that thinking they'll change the world - or at least are very opinionated (i'm not at all - lol). Why do they not voice their ideals louder? Why, if they think they are doing good for all mankind do they not speak what they know? Is it fear, or is it because they know that in reality they would not stand tall?
What things are worthy of fighting for, changing for?
Can a person change the world by being quiet in their little home with their families - one person at a time? I think so - especially if they are saved and pray to their God in heaven as well as do what He wills in their life.
Change - when should it take place, what should take place?
Philippians 4:6 (NASB) Be anxious for nothing, but in everything by prayer and supplication with thanksgiving let your requests be made known to God.
I guess in ending all I have to say is - if you feel you're doing something God wants you to do, then do it and do it boldly.