How to Change Airport Extreme Password

My new blu-ray player does not have a symbol that I use in my password. How do I change the password so I can connect it wirelessly? I have a guest network I would do this on so I don't impact my iMac, Apple TV, iPhone, etc, on my main network. If I reset Airport Extreme, then I must reset the password in all my wireless devices. How can I just change the guest network password?