Help, who has a brinsea polyhatch incubator?

[CocoPopz]

I'm struggling To get my temp right, I was just wondering if someone has the same one, roughly what line do they put it on for hens?
Here's I picture encase you don't know what I mean...

those little lines with the + on the right and the - on the left....just so I've got an Idea to work from!
Thanks