Which form to show when access denied in asp .net web

Hi, 

I am pretty new to asp .net, I am using VS 2013, I tried creating a web form project with the asp .net identity built-in forms.

I created a new folder with some forms inside it, and I added a specific web.config under the new folder and set access denied for anonymous user. when I tried to navigate to these new forms without login, it will redirect me to the built-in login form.

May I know which setting in the solution will redirect to this login.aspx when access is denied in any of the form?

~Derek