To change your password in Office 365 select My account at the top right of the screen and select My account.

On the left hand side select Security & privacy and click on Change your password.

You will now be asked to enter your current password followed by a new password. Select Submit to change your password.
Your new password will need to meet the Password complexities below.

Password Policy
- Password length: 8 or more characters
- Must contain 3 of the following 4 character types
- UPPERCASE
- lowercase
- Number
- Special character (!”@:? etc)