Should be simple right?

Hello, I'm a noob and may be missing something.  In my Digital Editions reader I want to change the highlighting color.  The settings icon I see in the library is for adding bookshelves; the settings icons inside the e-book are bookmark and TOC options.

Maybe it's not even possible to change the color?  Seems like there ought to be a general settings button though.

So far not pleased with this product.  Of course, it was free . . . you get what you pay for . . . I have 2 other apps for e reading but neither of them allow highlighting.

TYIA!