You can customize the toolbar in the file qa-plugin/wysiwyg-editor/qa-wysiwyg-editor.php, from line 138. For example, on line 147 change
"['RemoveFormat', 'Maximize', 'Source']".
The CKeditor site has various info on configuring toolbars: http://docs.ckeditor.com/#!/guide/dev_toolbar
Edit: just realized, there is a config.js file included in the plugin. Not sure if that is read by CKeditor but might be worth trying. I think you'd need to add a config.toolbarGroups setting like on the above link.