Change font size digital editions

I've downloaded digital editions for my iPad and am trying to read a book but the text is tiny! About 8pt.

I've read the instructions but can't find the 'reading menu' to change it. I can find everything else!  I'm not digitally challenged and am used to ereaders as I have a kindle but I've spent hours now trying to see where the bloody 'reading menu' is. 

Its not at the bottom or top of the book and isn't in app settings.

Please help!