Fiery,
Thank you for looking into this issue.
I have tried to Modify the Sensor Panel item for the external HDD temperature, changing the size, style, type, values, etc., but I cannot. That is to say; no matter what I change, the "OK" button remains greyed out so that I cannot apply the changes. With other Sensor Paenl items, the "OK" button is usable, even without any modification.
Also, why would that particular Sensor Panel icon, and only that one, be visible (and editable) for all versions of AIDA64 that use the Sensor Panel except the last three version as noted?
As always, your help is greatly appreciated.