CAUTION: when signing into 365 ensure the address on the top has microsoftonline.com or microsoft.com
To change your Microsoft 365 password.
Login at: https://login.microsoftonline.com/ (or goto https://myaccount.microsoft.com/ )
Goto your profile picture (top right) and select "View Account"
On the left hand menu select passwords
NOTE: the address for the password reset is: https://account.activedirectory.windowsazure.com/ChangePassword.aspx
You will need your old password to reset it.