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Why does XmlDocument read .config file, but ConfigurationManager does not? [duplicate]

I have added multiple app.config (each with a differet name) files to a project, and set them to copy to the output directory on each build.
I try and access the contents of each file using this:
System.Configuration.Configuration o = ConfigurationManager.OpenExeConfiguration(#"app1.config");
The code runs, but o.HasFile ends up False, and o.FilePath ends up "app1.config.config". If I change to code:
System.Configuration.Configuration o = ConfigurationManager.OpenExeConfiguration(#"app1");
Then the code bombs with "An error occurred loading a configuration file: The parameter 'exePath' is invalid. Parameter name: exePath".
If I copy/paste the config file (so I end up with app1.config and app1.config.config) then the code runs fine, however, I posit this is not a good solution. My question is thus: how can I use ConfigurationManager.OpenExeConfiguration to load a config file corretly?

I can't remember where I found this solution but here is how I managed to load a specific exe configuration file:
ExeConfigurationFileMap map = new ExeConfigurationFileMap { ExeConfigFilename = "EXECONFIG_PATH" };
Configuration config = ConfigurationManager.OpenMappedExeConfiguration(map, ConfigurationUserLevel.None);

According to http://social.msdn.microsoft.com/Forums/en-US/winforms/thread/3943ec30-8be5-4f12-9667-3b812f711fc9 the parameter is the location of an exe, and the method then looks for the config corresponding to that exe (I guess the parameter name of exePath makes sense now!).

To avoid this problem altogether, you can read in the config file as an XML file, for example:
using System.Xml;
using System.Xml.XPath;
XmlDocument doc = new XmlDocument();
doc.Load(System.IO.Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().Location) + "\\..\\..\\..\\MyWebProject\\web.config");
string value = doc.DocumentElement.SelectSingleNode("/configuration/appSettings/add[#key='MyKeyName']").Attributes["value"].Value;

using System.Reflection;
try
{
Uri UriAssemblyFolder = new Uri(System.IO.Path.GetDirectoryName(Assembly.GetExecutingAssembly().GetName().CodeBase));
string appPath = UriAssemblyFolder.LocalPath;
//Open the configuration file and retrieve
//the connectionStrings section.
Configuration config = ConfigurationManager.
OpenExeConfiguration(appPath + #"\" + exeConfigName);
ConnectionStringsSection section =
config.GetSection("connectionStrings")
as ConnectionStringsSection;
}
At least, this is the method I use when encrypting and decrypting the connectionStrings section for my console/GUI apps. exeConfigName is the name of the executable including the .exe.

How to access "user.config" of different application

The user.config file of an application can be accessed in C# by
ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.PerUserRoamingAndLocal).FilePath
Now, I need to get the user.config of a DIFFERNT application, identified by the fullpath to its exe in order replace current applications user.config by that one.
Any suggestions how to do so?
Edit: Please notice that I am interested in the user.config (ConfigurationUserLevel.PerUserRoamingAndLocal), not the application level settings like app.config or Application.exe.config. The latter is accessable by the OpenExeConfiguration(string), but is not what I want.

What about the overload that accepts a string?
var config = ConfigurationManager.OpenExeConfiguration(pathToAssebmly);
Anyway it´s a bad idea to bind your assembly that way to another one. You should consider to copy the config-file into all your assemblies and change the parts that are specific to a given one.
EDIT: As you´re interested in the user-specific setting you may use the following which is taken from here:
string configFile = string.Concat(appName, ".config");
// Map the new configuration file.
ExeConfigurationFileMap configFileMap = new ExeConfigurationFileMap
{
ExeConfigFilename = configFile
};
var config = ConfigurationManager.OpenMappedExeConfiguration(
configFileMap,
ConfigurationUserLevel.PerUserRoamingAndLocal);

Cannot read settings using ConfigurationManager [duplicate]

I have a WinForms .exe with an App.config that has a bunch of User Scoped Settings that are set at runtime and saved.
I want to be able to use the WinForms app to change and save the settings and then click on button to do some work based on the those settings.
I also want to read the user settings in the same .config file from a sep. console app so I can schedule to work to be done as a scheduled task.
What is the best way to be able to do this?
Update:
I tried the reccommendation of using ConfigurationManager.OpenExeConfiguration as described in some of the answers like so.
Configuration config = ConfigurationManager.OpenExeConfiguration("F:\\Dir\\App.exe");
but when I try to retrieve a User Setting like so.
string result = config.AppSettings.Settings["DB"].ToString();
I get a Null reference error.
From code in the exe however the following correctly returns the DB name.
Properties.Settings.Default.DB
Where am I going wrong?
Update 2:
So based on some of the answers below I now can use the following to retrieve the raw XML of the section of the user.config file I am interested in from sep. ConsoleApp.
System.Configuration.ExeConfigurationFileMap fileMap = new ExeConfigurationFileMap();
fileMap.ExeConfigFilename = #"D:\PathHere\user.config";
Configuration config = ConfigurationManager.OpenMappedExeConfiguration(fileMap,ConfigurationUserLevel.None);
System.Configuration.DefaultSection configSection = (System.Configuration.DefaultSection)config.GetSection("userSettings");
string result = configSection.SectionInformation.GetRawXml();
Console.WriteLine(result);
But I am still unable to just pull the value for the specific element I am interested in.

this should do it :
var clientSettingsSection = (System.Configuration.ClientSettingsSection)(ConfigurationManager.GetSection("userSettings/YourApplicationName.Properties.Settings"));
var setting = clientSettingsSection.Settings.Get("yourParamName_DB_");
string yourParamName_DB = ((setting.Value.ValueXml).LastChild).InnerText.ToString();

You can use the ConfigurationManager class to open the configuration file of another executable.
Configuration conf = ConfigurationManager.OpenExeConfiguration(exeFilePath);
// edit configuration settings
conf.Save();

See ConfigurationManager.OpenExeConfiguration

If you are setting these values per user basis you may need to use the ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel) method instead of the current method you are using now.

ExeConfigurationFileMap fileMap = new ExeConfigurationFileMap();
fileMap.ExeConfigFilename = Environment.CurrentDirectory + "\\MyApp.exe.config";
//i have config in the same directory as my another app
System.Configuration.Configuration config = ConfigurationManager.OpenMappedExeConfiguration(fileMap, ConfigurationUserLevel.None);
var settingsSection = (System.Configuration.ClientSettingsSection)config.GetSection("userSettings/MyApp.Properties.Settings");
var setting = settingsSection.Settings.Get("MySetting");
var param = ((setting.Value.ValueXml).LastChild).InnerText.ToString();

If you know the path to the config file try:
System.Configuration.Configuration config = System.Configuration.ConfigurationManager.OpenExeConfiguration("configPath");
string myValue = config.AppSettings.Settings[ "myValue" ].Value;

Can't modify app.config file with no error

I'm struggling with trying to modify the appSettings part of the app.config file of my application. However I'm not receiving any error/exception and I can read values without any problem.
Here is how I tried to set values :
ConfigurationManager.AppSettings.Set("DaysLeft", Days.Text.ToString());
//
System.Configuration.Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
config.AppSettings.Settings["DaysLeft"].Value = Days.Text.ToString();
//when I debug the app, I notice that the value is changed in the previous line
The app.config file isn't being modified.

System.Configuration.Configuration config =
ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
config.AppSettings.Settings["DaysLeft"].Value = Days.Text.ToString();
config.Save();

You need to save your changes
config.Save(ConfigurationSaveMode.Modified);
Also, if you want to reload the app.config
ConfigurationManager.RefreshSection("appSettings");

How to update an value in app.config file?

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.

This code should work:
Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
config.AppSettings.Settings["IP"].Value = "10.0.0.2";
config.Save(ConfigurationSaveMode.Modified);
ConfigurationManager.RefreshSection("appSettings");

As per my knowledge you can't persist the updated value in App.config.
If you want to persist the config value,do the normal XML operation.