Your personal settings at WordPress.com can be accessed via
Users -> Personal Settings in your dashboard.
Admin Color Scheme: Choose from nine color schemes to use with your WordPress.com dashboard.
Keyboard Shortcuts: Check this box to enable keyboard shortcuts for easier comment moderation. Please see http://codex.wordpress.org/Keyboard_Shortcuts for more information.
Twitter API: Did you know that you can use Twitter-API-compatible tools to access WordPress.com?
Browser Connection: Choose whether to use HTTPS when navigating your WordPress.com dashboard.
Primary Blog: You can choose which blog you want to be your primary blog here. If you only have one blog there will be no dropdown.
Proofreading: WordPress.com uses After the Deadline, a powerful proofreading service to make sure your prose is top-notch. You can specify which parts of the service you want to use here.
Username: This is your current username. This username can be changed by following the directions here.
E-mail: Required. You may change this, but note that e-mail addresses cannot be shared among accounts. That is, one e-mail address cannot be registered with multiple accounts. You will need to confirm by e-mail when changing your e-mail address.
Although your e-mail address will not be displayed publicly on WordPress.com, when you submit a comment while logged into your account, the e-mail address will be transmitted to the blog’s owner/administrator.
Website: Not required. This is the URL that will be linked to your username when leaving comments on WordPress.com blogs. Please note that this is stored at the time of the comment, so if you do update this, it will not affect past comments (only those made in the future).
New Password: Use these fields to change your password. Both fields must match in order for the password to be successfully changed. Please use the strength indicator as a guide when choosing a new password. Your password is vital to your blog’s security!