Want to modify the default CK Editor, but not sure which attributes can be set? You can find a full list of CKEDITOR configuration settings here: docs.cksource.com/ckeditor_api/symbols/CKEDITOR.config.html
These changes can be applied to the ~\CMSAdminControls\CKeditor\config.js file, after which you will need to restart the application, clear the application cache, and clear the browser cache depending on which browser you are using. You can restart the application and clear the application cache from Site Manager -> Administration -> System.