I have been studying just writing, but I wanted to try out definition, too. I went to settings and selected it there. I then got a huge list of due cards from basic decks that I am not interested in any longer (this is probably leftovers from when I first started using Skritter last year), so I decided that I only wanted to study definition in the deck I am currently working on. I turned off definition in the main settings, and selected it in the current deck.
The help text explains that I need to relearn old words that I want to add is to “manually re-learn them from the info screen”. However, that does not seem to work. I select a card, go to stats, and see only the writing card. I then relearn it, and go to stats again, but I still only see the writing card.
Am I doing something wrong?