To Change your Windows Live ID password:
1. Sign in to your account summary page with your Windows Live ID.
Your Windows Live ID is the e-mail address and password used to sign in to Windows 8.
2. In the Account Information section, click Change next to Password.
3. On the Change your password page, verify that the e-mail address in the Windows Live ID field is correct.
4. Type your current password in the old password text box.
5. Type a new password.
The Password strength meter will help you determine whether your password is considered a strong password.
6. Retype your new password for verification.
7. Optional: For added security you can set your password to expire every 72 days.
Click the Make my password expire every 72 days check box.
Please note that some services require a password change every 72 days. If you use one of these services, automatic password expiration may already be set and cannot be changed.
8. Click Save.

Thanks to troll45 for sharing.

Original thread: error after changing login password in windows 8