DevIT
  • Open your Central Administration site
  • From Central Administration, in the Application Management section, click Manage web applications
  • Select your Forms Web Application, click Authentication Providers
  • From the Authentication Providers page, click Default
  • On the Edit Authentication page, in the Sign In Page URL section, select Custom Sign In Page, enter:
    /_login/extranetlogin.aspx
  • Save Changes

Now If You close browser and open your FBA application, You should see a new login screen: