Used Macbook Pro, trying to change the admin/user name. I've tried to change it, but wasn't successful.

I'm relatively new to Mac, and I'm still learning my way around my Macbook Pro 2010 from this summer. I was using terminal to do some class in work, and I keep noticing that the user name is something close to 'hello$' (as shown in the screenshot). I purchased this from another Mac user, and some of the settings weren't restored; like the user name and default language on the notebook was in Chinese.

In short, how do I change the user name. Also shown in the screenshot is my name, as you can see I already tried to change the computer's name/admin name.

also, if anyone could answer this simpler question: How do I save the preferences on my terminal to remain the color I have now. Everytime I quit Terminal it reverts back to the same black text - white background.

Thanks in advance,

G