"There is no way you can change default search engine BUT it is possible to add other search engines. First off you have to change data saving to 'extreme' then go to any search engine site you'd want to add, let's say bing.com then press and hold the empty search box a window pops out and click on 'add search engine'. That's it. Switch back the data saving options and there will be a new option in the search box."
Although the directions are for ipad, it worked for me in the latest version of Mini on android
Online emulator http://demo.opera-mini.net/public/ works - so it is independent on browser java plugin - as microemulator doesnt work, as browser use outdated java plugin, and as it is said on Oracle java check - Mozilla 52 versions on - does not use java plugins.
@williamearle18 You don't say what platform but there are old versions going back to 5.0 for Android at: http://ftp.opera.com/ftp/pub/opera/android/mini/
If you poke around in ftp.opera.com you might find something for other platforms. Otherwise Google is your friend as always.
Keep in mind that old versions night not work well or at all do to server side changes.