Changing External Dictionary

How do I change the external dictionary after choosing one in the mobile app?

I was reading a passage yesterday and used the external dictionary. The app gave me many different options. After I had picked one, I could not find a way to change to another one. What can I do?

What may have happened is you selected "default". If so, go to the hamburger menu (3 bars uper rh corner)>reading settings>clear default dictionary selection.

Thank you, it worked.