How to deauthorize all devices.

I have tried to deauthorize all my devices several times. I have pulled down the ACCOUNT several times in order to deauthorize all, as per instructions. But there are only 2 choices, "Authorize this computer" or "Deauthorize this computer". No deauthorize all devices devices so I can re install them as the instructions recommended. When I try to retrieve songs on iTunes it tells me I cannot download music onto the new device computer. It says I have 5 devices already. I have deauthorized the old one, but it still gives me the same message. Any ideas?