Thanks yr advice bigmike7.
Revo Uninstaller could not find any Orbit Downloader files or parts therof.
There are complaints in Firefox and Downloader Forums from others about Downloader changing home page uninvited but no edits or effective advice as to how to remove.
Ran Eusing Reg Cleaner, CCleaner, Malwarebytes n others but bug still there.
Please , any other advice.