If I went back in time I could prevent a great many wrongs. However every action taken in this world has led to this current situation and more importantly since ALL humans are selfish to a degree and would change something that has affected them in the past I immediately think of what makes the short list for what I would change:

+ Not moving to my brothers 4 years ago when I had the chance, that would have infact have changed all of the other things I have on this shortlist. I should have gone to his and lived there with him.

I then think of what or where would I like to go in the future I could go see how I turned out secretly but in doing so I would change that future irrevocably because since the time machine is single use it will never come to pass for me because I am in the timezone of the future trapped.

I would rather go back 4 years and move to my brothers but having the knowlege of now I would be able to steer my life in directions I want to progress in.

EDIT: I suppose if I had to do a unselfish reason I would move backwards in to the past having learnt a lot of stuff about energy production and methods of renewable power and teach the people of the victorian era the secrets of electricity from renewable sources rather than steam and coal.