How to place a users role after username in Forums
If you can find the display in views.

You can add a  "User: Roles" Field. Mark it as excluded.

Then

Under "user: name" field. select "Rewrite the output of this field" and include the [rid-role] token in the username.

Be sure to add the "role field" before "user field" otherwise the token will not be available.

Example