Log into your profile on the site, and follow these steps:
1. Select the menu icon on the top right of the page (to the right of your picture), and under the menu that appears choose Settings, then Account Settings:
2. Once on the Account Settings page, click change next to Password to update this information.
3. Type in the new password you wish to use. Type it in again to confirm the new password. You can then select change password when you're done.