This is my code:
Configuration configuration = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
KeyValueConfigurationCollection settings = configuration.AppSettings.Settings;
settings["IP"].Value = "10.0.0.2";
configuration.Save(ConfigurationSaveMode.Modified);
when I break on settings["IP"].Value
line, i get the correct value.
The method completes without any errors but app.config file remains unchanged.