Select Security from the navigation across the top of the Account home page.
On the Security basics page, select Change my password.
If you have security info on your account, you'll see the Verify your identity form with a partial view of the phone number or email address you chose for account verification. Select the one where you want to receive your code and enter the requested verification information. When you're done, select Send code.
Enter the code you received and select Verify.
On the Change your password page, enter your existing password and then add your new password. When you're finished, select Save.
If you don’t have the necessary security information and can’t receive a verification code, you may need to use a different verification option, see Recover your Microsoft Account.