The only staff that can change your name are Dacon and Morph and they are generally too busy to deal with age changes.
Unless you are applying for staff you age has no impact. If you are applying for staff, you can just explain that in the application. We aren't usually too concerned about players saying they are younger than their forum age. We are more suspicious of players claiming to be older than their forum age, especially if it affects if they meet the minimum requirements.