My Network Preferences obstinately refuses to change the remembered password to a network, even though it's wrong!

Question

I am having trouble connecting to my school's wireless network. Initially I couldn't connect at all, but someone helped me by going into the Network Preferences and changing the password stored there (it was trying to use an earlier one that was used for the schools old network). That worked fine until I changed my password from the random numbers the school gave me to something I could remember.
Now, no matter what I do, I cannot get it to use the new password! What I mean is that when I go to the Network in question, click the tiny pencil shaped button, type in the correct password, click Add, then Apply, I come back to check what the new saved password is and it's still the incorrect password. Instead of saying it was connected, it would show full bars but say Self-Assigned IP.
Despite this, the computer did have the correct password filled in elsewhere. In the 802.1X section of the Advanced Network Preferences there is a User Profile named after the Network that has the correct password in it. This has been true during periods where it was working, as well as during times when it wouldn't connect.
I've tried deleting the wireless network from my list of remembered networks and then re-adding it with the correct password. When I do this, it comes back with the incorrect password already filled in! Maddening.
I've tried unchecking the box that says "Remember all networks this computer has joined", this worked with limited success, allowing me to connect again, but then, half an hour later, it stopped working and won't even suffice as a temporary fix anymore. To the pit with this!
To get online and type this I went to Keychain Access, thinking that is how my computer was remembering the incorrect password and thus, repeatedly filling it in. However, deleting all mention of this Network there had no effect. It was only after deleting some authenticated certificates that I was allowed to reconnect. I haven't the faintest idea why this made it work, the Network Preferences is still refilling in the incorrect password no matter what I do, but for some reason it is working... as of now.
While I was typing this, I lost connection again... I returned to Keychain Access and did all the things mentioned above, now I am posting this before I am forced to do so again.
Thank you.

Answer 1

I am having trouble connecting to my school's wireless network. Initially I couldn't connect at all, but someone helped me by going into the Network Preferences and changing the password stored there (it was trying to use an earlier one that was used for the schools old network). That worked fine until I changed my password from the random numbers the school gave me to something I could remember.
Now, no matter what I do, I cannot get it to use the new password! What I mean is that when I go to the Network in question, click the tiny pencil shaped button, type in the correct password, click Add, then Apply, I come back to check what the new saved password is and it's still the incorrect password. Instead of saying it was connected, it would show full bars but say Self-Assigned IP.
Despite this, the computer did have the correct password filled in elsewhere. In the 802.1X section of the Advanced Network Preferences there is a User Profile named after the Network that has the correct password in it. This has been true during periods where it was working, as well as during times when it wouldn't connect.
I've tried deleting the wireless network from my list of remembered networks and then re-adding it with the correct password. When I do this, it comes back with the incorrect password already filled in! Maddening.
I've tried unchecking the box that says "Remember all networks this computer has joined", this worked with limited success, allowing me to connect again, but then, half an hour later, it stopped working and won't even suffice as a temporary fix anymore. To the pit with this!
To get online and type this I went to Keychain Access, thinking that is how my computer was remembering the incorrect password and thus, repeatedly filling it in. However, deleting all mention of this Network there had no effect. It was only after deleting some authenticated certificates that I was allowed to reconnect. I haven't the faintest idea why this made it work, the Network Preferences is still refilling in the incorrect password no matter what I do, but for some reason it is working... as of now.
While I was typing this, I lost connection again... I returned to Keychain Access and did all the things mentioned above, now I am posting this before I am forced to do so again.
Thank you.