One surefire method to stop automatic updates is to remove execute permissions from Opera's opera_autoupdate executable. This prevents Opera from ever checking for updates. Run this command in a Terminal window.

chmod a-x /Applications/Opera.app/Contents/MacOS/opera_autoupdate

Restore update checking with this command:

chmod a+x /Applications/Opera.app/Contents/MacOS/opera_autoupdate

The "Show full URL in combined search and address bar" preference displays the full URL. Why gray-out the portion of the URL the preference is designed to display? For example, opera.com is black, but the rest is about 66% gray ** squint **

https://forums.opera.com/post/discussion/130135

To provide a preference and then make it hard to see seems to defeat the reason for the preference, doesn't it?