Change existing XML tag attributes in project resource

I have an XML file in my C# project resource and I want to change some attributes programmatically. I can load the XML from resource and change the attribute value using this code:

var res = Assembly.GetAssembly(typeof(Global.Configuration))
                  .GetManifestResourceStream("MyNamespace.Resources.Configuration.xml");

var xReader = new XmlTextReader(res);
XDocument loadedXml = XDocument.Load(xReader);
loadedXml.XPathSelectElement("//configuration//setting/autosave")
       .Attribute("onoff").Value = chkAutoSave.Checked.ToString();

But how can I save the changes in my XML?