Touch Changing epub font

I picked up a Google Nexus 7 recently for a totally different purpose than reading books but since it came with some credit I purchased Moon+ Reader Pro and tried it out.

I've been having problems with the font on some epub books from a couple of smaller publishers. Basically the serif font it comes was the only one that the Touch will use. I just assumed that the epub books were badly created and since its a smaller publisher didn't bother to much about it.

However with Moon+ Reader Pro reading the same ebook I can change the fonts to a sans serif one which I find easier to read on a screen.

I seem to recall that most books are printed at a minimum of 300 dots per inch, many at 1200 dots per inch and at these resolutions I read faster with a serif type face. Computer monitors are roughly 75 dots per inch and sans serif shows up better at this resolution, I suspect the Touch screen resolution is about 120 dots per inch and I do find it easier to read a sans serif typeface on the device.

Anyone any suggestions about how to change the font on the touch? Other than hope for yet another new version update?

Thanks John