Digital editions not in the list of default programs

While Digital editions is in my list of apps it's not in the list of default programs and cannot be selected to open epub files. Acrobat always jumps in and tells me it cannot open that type of file.

How do I get Digital Editions into the  default programs list so as to make it the default?.

Also, I have Adobe Acrobat as my default for ,pdf files but I still have to select it to open a PDF file. Surely having it marked as the default, that should not be necessary or is there some way of opening a pdf without needing to got to "open with"?