Question: Mercenaries

I wanted to level my Alchemist with a Level 6 Archer Mercenary in Geos but all she do is stand there and wait for me to manually control her attacks and use her skills.
I know that Mercenaries can walk/cast skills on their own like my own Homunculus used to do on Renewal.
I looked and tried to edit/config the AI by myself but I don't understand a thing!?

So I wouldn't mind to have some help over here.