Personally, I'd change both. If you have one of the early superhubs (before Hub 3, which all had the same default settings password to log into the router) then it is particularly important to change the default settings password to something new and secure.
Many thanks for the advice, I thought the advice to change to the settings password arose from earlier hubs with the default pw 'changeme'. However I have Hub 3. If however the settings password is changed will the original WiFi password remain active?