I've gone through all of the steps to reset my Firefox browser and attempted to change my search engine from Duckduckgo to Startpage. Every time it works a couple of times then Duckduckgo hijacks the search engine back to itself. I've deleted this search engine, reset my browser, said yes to prompts by Startpage to be the default browser, and tried everything that I can think of. Very, very frustrating. And I start to worry about the security of the Firefox browser itself. Any ideas?

Thanks, David