Digital Editions

I just started using Digital Editions a week to access library books.  I have worked it out except how to open the Text Size box.  Instructions say to tap T at bottom of page.  Mostly this doesn't work and I have opened the box only twice.  Other instructions say to use things on Toolbar but I don't have a Toolbar.  I have uninstalled and installed Digital Editions twice. I am using an Android tablet and haven't had a tablet before.  I know the Text Size box is there but just can't find it.