Back button focus confusion on Canon 1D mk4

[Braddersphotography]

Hello, slowly upgrading my gear and gone up from 5dmk 2 to a 1Dmk4.
I think I've set back button focus on the 1d but instead of it being triggered by the AF-ON button it's the * button that does the focus lock.
Does this sound correct?

 

[Braddersphotography]

You can change it in custom functions.

I know, but never know which setting to choose. Any idea which one? Is it not right on the * button then?

 

[john.margetts]

Us the button that works best for your hands. There is no correct.