Originally Posted by Duiker
Pushing 'up' or 'down' on the D-pad will change the font size respectively (on books where the font size scaling is not messed up by the kobo software)
Want to clarify that the Kobo software (either the desktop application, or the eReader firmware) does not interfere with font rescaling on ePubs. We use Adobe's Reader technology to render epubs, and if your epubs have a fixed absolute font size specified, we can't change it out of the box.
We are working on workarounds for the issue, and hope to have an update out soon (in the next 7-10 days).