it’s not appearing on an option on my screen in the way it is described in the help documentation.
Hi Andy - sorry about the confusion with this!
You can change your password by first logging in and then clicking on the account menu at the top right of your screen (this is where your name is) and selecting ‘View Your Profile’
In the dialog that comes up you will be able to select the ‘Change Password’ button at the bottom. The next screen will ask you to verify your current password before entering a new one.
Hope that helps!