Airplay issues

I have a computer that stores my itunes account. I had a Pioneer VSX1121K receiver that had airplay and worked on my ipod or computer. The Pioneer died. I replaced it with a Yamaha RX-A740. which works great with my ipod on airplay but when I go to my itunes on my computer the Pioneer still shows up and says it cant find it and the Yamaha doesnt show up. How can I correct.