Changing your Community Username
Go to your Settings by clicking on your username in the upper right corner and choose My Settings.
There you can change your username.
Changing your Community Email Address
Your email address is part of your My JMP ID. At this time, there is no method to update your email address. You will need to create a new My JMP ID (and Community username). To have your new Community account linked to your previous Community account, open a case with Support (info@jmp.com).
Next: Community Ranks