You can remove the old blog link and link your active blog to your username easily. Dashboard -> Users -> Personal Settings -> then scroll down to Account Details. Then scroll down to where it says ‘Website‘ select the URL for your primary wordpress.com blog and then save changes. When you do that it will also change on your forum profile.
For your forum Profile see here at the top of the page Welcome, staked | Log Out
Also if you click “member” under your username in any forum thread you can access your forum profile.