Automating Arpeggiator in Logic

I recently started using Logic (was using Cubase), and I can use the arpeggiator and change its settings, but i cannot see how to automate it, for example changing the direction for different parts on the song. The usual method does not work (i.e. there are none of the arpeggiators controls in the drop down). I could create 2 arpeggiators with different settings and distribute the clips between them, but I was wondering if this is the right way to do it, or have I missed something?

Any help mucho appreciated!

Mike