Seems a rather circuitous method, but found it tyvm. Similar utilies (AV software as one example among many) show a check list of drives to select from, then scans those drives.
The drive I wanted to scan is an external, and had to add it to the list of drives to scan by browsing (not select from a list).
Even though I selected the ext. drive (and C appeared to be inactive), the utility still scanned both drives. Guess one must remove other drives as opposed to just highlighting the one you want to scan.
Perhaps that's what the person you referred to did - highlighted her/his external drive, then when s/he saw the C drive being scanned assumed that the external should have been running?
thx for the assistance
PS: Just tried again, and removed C from the scan profile so that just the ext. drive showed, but it still scans C before the external.