When you get in, look at the moodle logs and see what it is telling you about the login attempts. Then go to Edit Profile and see if you have the option to see your password...
Is this just a manual account? You aren't authenticating through LDAP or another system are you?
Couple of possibilities I can think of - first, you are just not putting it in correctly (seems unlikely after so many attempts but still possible) - second, something is not allowing that field to update and it is stuck at your original password...