I don't use IE, so I hadn't installed the DDG search until just now, testing what you've reported. I followed the instructions and allowed DDG to be added as a search engine, then selected DDG as my default search engine and it worked as described, total time was <1 minute.

After doing this, DDG won't be listed among your programs, it is just available as a search engine and can be set to be your default search engine for IE.
posted by x.15a2 Community Leader2 years and 26 days ago Link