It might not be the clearest, but this is one of the best screenshots I have.
If you notice where it says "Freddi" on the white tab and on the little thing that shows my HP, Mana, XP, Gold, and Stats/Item/Armor/Skills?
The tab where it says your name on it, there should be a pencil thing there.
Click and that and you
should be able to find a list of titles you've earned.
Click on one of them that will change your title.