Use customize yourself. You see your own ava and several tabs on the rigth side. Choose “Your body” – hair style. You get a list of all possible items – the ones you already purchased (in shop) are marked. You also see all possible items, the ones you haven't bought yet are marked with an “x” and not selectable. After changing your hair, you have to save.
if I bought a shiny black hair style but when i bought it and used it is yellow