IIS Express stores its configuration settings in the %USERPROFILE%\Documents\IIS Express\config\application Host.config file which eliminates the need for administrative permissions for changing it.
As a consequence when you uninstall Visual Studio, the webserver configuration remains in the user’s profile folder.
Visual Studio 2015 has moved the IIS Express configuration file from My Documents into its own hidden directory and tells to use that configuration file.
While this may sound like a good idea when you have multiple web applications with conflicting configurations, in fact it's not when you have web applications with custom configurations at all.
I have not found many references to this problem and have not figured out what to do to fix it, but I have learned to deal with it, if rather crudely. If I need to make some changes to this file, like allowing the application to use Windows authentication, I edit this file once and I'm done.Now with the new location, I may need to make these changes multiple times.If you often create new web applications in Visual Studio, it is a good practice to clean up IIS configuration once in a while.Because there is no GUI for IIS Express, you can edit the application Host.config file directly or you can use the command line.