That's funny. Your leg is a perch. My chickens think my legs are perches, too. They also take liberties with using my legs and arms as napkins on which to clean their messy beaks.
Back to the problem. When trying to convince a chicken to change their behavior, no small task, you can only start to make progress if you make the old option as unappealing as possible.
I had a similar problem with a young pullet insisting on sleeping out in the run on top a partition. I solved it by stretching plastic deer netting over the partition so as to make it impossible to perch there.
Later on I discovered why this pullet was sleeping in the run. Her fellow pullet was hammering her with her beak when she tried to roost. It was so stressful and unpleasant, she decided to move out.
You're already putting them inside at night. Continue to do that. But figure out a way to block off the perch they find so attractive outside.
In the future, there's a better way to integrate chicks than waiting until they're full grown, which only makes them more of a threat to the adult chickens. I wrote an article about all the advantages of brooding outdoors in the run. It's listed below. You need to copy it onto your browser to access it.
