Does the vertical menu work for you? Its on the 'Menus and Links' menu under the pencil icon.
If you switch to the vertical menu the text on the labels is left justified.
Ok, got it.
A future version of the app may have more control over this kind of thing, but at present the best option is to load a background image with a guide line on it. Then set that, align the text, then remove the background image.