Only the pre-defined search engines that come with Opera can be set as the default one.

@leocg Evidently I broke a rule - sorry about that. I will read the instructions and repost appropriately. Thank you for your patience.

For this to happen, both Opera and Ecosia need to want it, and it has to be profitable for both. So did you already contacted Ecosia? What they say about it? Di dthey already try an agreement with Opera?

Google doesn't separate search results that much anymore - like they used to do for different language areas. Sure China still get's the treatment. If Opera continues to be the only browser with forced default engine ~ step 1 would add option to choose a country code (ccTLD) from a short list including .com!

@m-n-g I think it is only work in address bar not in Speed Dial bar. So, type in address bar Edit : Sorry, I didn't read this forum is for Linux. I use Windows 10 v.1709 (RS3)

@silas229 Except, maybe, for Edge/IE and Chrome, almost all browsers get their revenues from searches and from pre-added bookmarks/speed dials.