To change the bookmarks link, you need to edit the lua files, but the web search url is in the registry, however the link simply opens in your default browser. since the older version is opening for you, that means that the new one is not set as your default browser.
Try the following registry to make Opera 10 your default browser:
Code:
[HKEY_LOCAL_MACHINE\Software\Microsoft\Shell\Rai\:DEFBROWSER]
"1"="\"\\Windows\\OperaL.exe\""
to
Code:
[HKEY_LOCAL_MACHINE\Software\Microsoft\Shell\Rai\:DEFBROWSER]
"1"="\"\\Program Files\\Opera Mobile 10\\Opera10-armv4i.exe\""