Switching between my children's accounts

I have 3 children, each of whom have an account.  We can't seem to properly log out of my first child's account for my other children to access theirs.  (My first child's account remains listed at the top drop down menu, and is among the list of children on the page.).

How can I/they switch to get into their own lessons?

(It looks like this question is posted under my son's name...which may be part of the challenge...perhaps I inadvertently set him up as a parent?)