I have type the line https://duckduckgo.com/?q=%s&t=oen to create a new search engine, Keyword d, but it does not move to the upper section to make it default. I have also installed duckduckgo as extension.
I guess i have to modify the code of Opera? . I'm using

Version: 20.0.1387.82 - Opera is up to date
Update stream: Stable
System: Mac OS X 10.8.5 64-bit