Hiya I have a gray and when he goes to poo i send him back to the stand and when he has done a poo on his purch i say good boy have you doine a poo on your purch and dont say anything when he poos where he shouldnt.. but he i do see him about to go i stand up and shoute quick back to your purch for a poo... and 99% of the time he does go back to the play stand purch for a poo.... then you get a woooow because he knows hes a good boy...lol
Hope this helps...
We also have a yellow nape and i do the same if he bites I lurnch him back to the stand and say back to your purch if your going to bite and that works most of the time to....