Change the Contents of _ViewStart.cshtml file. You can also use if elseif statement.

@{

    string CurrentController = Convert.ToString(Context.Request.HttpContext.Request.RouteValues["Controller"]);

​

    switch (CurrentController)

    {

        case "User":

            Layout = "_New_Layout";

            break;

        default:

            Layout = "_Layout";

            break;

    }

}  

Note: You can add as many case conditions as you want depending on your need.