using System.Configuration; static void Main(string[] args) { UpdateConfigAppSettings(); ReadConfig(); Console.ReadLine(); } static void UpdateConfigAppSettings() { Configuration cfg = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None); cfg.AppSettings.Settings["UserName"].Value = "Fred"; cfg.AppSettings.Settings["UserPwd"].Value = "FredPwd"; cfg.AppSettings.Settings["IsRemembered"].Value = "True"; cfg.Save(ConfigurationSaveMode.Modified, true); ConfigurationManager.RefreshSection("appsettings"); } static void ReadConfig() { Console.WriteLine($"{ConfigurationManager.AppSettings["UserName"].ToString()} " + $"{ConfigurationManager.AppSettings["UserPwd"].ToString()} " + $"{ConfigurationManager.AppSettings["IsRemembered"].ToString()}"); }