It doesn't matter whether you are young or old to wear a pair of round glasses. In these years, more and more people consider it to be a very important factor that if the glasses look beautiful when people are choosing glasses. Round glasses is just as same as other kind of glasses except its shape. As you young people, you should pay more attention on the lens and optometry. So I strongly advise you to go to a regular store to buy your glasses.
Well, I think whether it is suit for you depends on your face instead of older people wearing them. If you have a round face, you'd better not wear a pair of round glasses again. There are some tips about faces and glasses. It may make you looks rounder and rounder. Wide face is not fit with round, oval or small glasses, glasses with wide, square or angular glasses will be better. Lozenge faces are also fit with round or oval glasses. But these are something public. I think teenager wear round and black glasses looks very cute.