Likebook Mars - changing default dictionary

Hi:

I use the Kindle app for reading my mobi format books since I find it suits my needs more than some of the other reading apps I have tried, including the Mars default reader. However, one thing that I find very frustrating is that I can't change the default dictionary. Whenever I long press a word to get the meaning it always goes to the default dictionary for that language (eg el Diccionario de la lengua española). When I select the Change Dictionary option I can change to the dictionary that I want (eg the Collins Spanish Dictionary) but the next time I look up a word it reverts back to the original default dictionary. Is there a way to change the default dictionary in the Kindle app to the one that I want?