First, you need to understand that editing this the way you did will only change the name for the new users. (As this is what gets inserted into the alias field). To make this change otherwise, so Alias is irrelevant, you need to edith the Forum_User code's Info object. This inherites from DNN's user so where it sets the alias based on a database value (retrieved from the forum_users table) you make this a public read only property that is the value of the current membership.displayname (or whatever it is exactly from core for display name). This is how I am editing the option in the source now to implement that feature we are talking about. I know this works, but there are other areas affected by making this a read only property. These places, however, become irrelevant for the most part because you will no longer need Alias.

Well after sometime learning more about asp.net, dotnetnuke, visual studio and compiling i have answered my questions and a once php program has become an asp.net convert:

It was dnnUser.DisplayName not dnnUser.Membership.DisplayName and once i compiled the forum solution it worked!!