first add your favorite searchengine to the searchengines in the list
I have the Dutch version so I'll give the buttons-
in Extra (could be options in english) -
use Shift F12 -
panel choice= buttons -
click; search -
now simple drag and drop the new searchengine to the bar next to the original.
now rightclick on the unwanted original and click remove from the bar

the new searchengine is now the only searchengine and Google is out.

Hi there,
For some reason my default Opera search engine is google.co.kr, which is strange because I don't actually speak Korean or have Korean language settings as far (as I know). I want to change the default search engine to google.com but under Preferences > Manage Search Engines it doesn't give me the option to edit Google Search, and if I add an "Other Search Engine" I can't set it as Default.
Any help is appreciated.

The redirection from google.com to any other domain is based on your IP. If you've got a proxy connection using a Korean IP address, you will be most likely redirected to that country's specific domain, according to your IP address (if Google has a custom page for that country). This is not something that Opera can fix since it's not a bug.

You cannot set non-standard search engines as default because third-party programs started changing users’ searches to malicious websites. Until we can fully protect against this attack, the ability to set a non-pre-installed search engine was default was removed.
As for changing the auto-discovered location from within the browser, that is being discussed. Its very annoying and inconvenient when it fails. Fortunately, it “just works” for the majority of users.

Any update on this?

The only thing / problem, one can NOT make any search engine from that list as the default one.

Which does look like that Opera is sponsored either by Google, Yahoo or Bing.

The goal of limiting the list is to counter malicious search engines, so if a search engine has proven itself a reliable and trustworthy, why not add it to the list?

Why not add Duck Duck Go to default search engines list?

Because then everyone who does not use Duck Duck Go will ask, 'why not add (insert their preferred search engine) to the default search engine list ?.'
The default search engine list would end up being huge if this were to happen. Best wait till Opera sorts out how to implement a way to allow users add default search engines without compromising the browser or user security.

So, add them, who cares if there are 1000 search engines available. Better than reducing functionality. In the specific case of DuckDuckGo, it should definitely be in the built in default list as its addition would restore a function which existed in previous versions of Opera!

Opera tends to attract users of a higher than average technical skill level, dumbing the browser down in the name of "security" is not appealing to us. Maybe it would be best to keep the shields up by default, but provide an option for the rest of us to make Opera work the way we want it to.

Why not add Duck Duck Go to default search engines list?

Because then everyone who does not use Duck Duck Go will ask, 'why not add (insert their preferred search engine) to the default search engine list ?.'

The default search engine list would end up being huge if this were to happen. Best wait till Opera sorts out how to implement a way to allow users add default search engines without compromising the browser or user security.

As for changing the auto-discovered location from within the browser, that is being discussed. Its very annoying and inconvenient when it fails. Fortunately, it “just works” for the majority of users.

Still outstanding questions though: Why does this issue arise? Why can't localization be changed from the Preferences.. window? And why can't I set an "Other Search Engine" as a default?