To completely disable URL autocomplete in Safari on your MacBook Pro running macOS 14.3, you may need to take additional steps beyond the preferences settings. Here's what you can try:
1. Disable Autofill: In Safari, go to Safari > Preferences > Autofill. Make sure all the autofill options are unchecked, including "Using info from my contacts", "User names and passwords", and "Credit cards".
2. Clear Bookmarks: Clearing your bookmarks can prevent Safari from suggesting URLs based on your bookmarks. To do this, go to Bookmarks > Edit Bookmarks, then select all bookmarks and delete them.
3. Check Extensions: Some Safari extensions may also affect URL autocomplete behavior. Disable any extensions you have installed and see if that helps.
4. Reset Safari: Go to Safari > Clear History, and choose "All history". This will clear all browsing history, cookies, and other website data.
5. Check Keyboard Settings: It's possible that macOS's keyboard settings are influencing autocomplete behavior. Go to System Preferences > Keyboard > Text and check if there are any text replacements set up that might be causing unwanted autocompletion.
6. Use Private Browsing: While not a permanent solution, you can use Safari's Private Browsing mode (Command + Shift + N) to prevent autocomplete from using your browsing history or bookmarks.
If autocomplete still persists after trying these steps, it's possible that Safari's autocomplete behavior cannot be completely disabled through settings alone, and you may need to explore third-party solutions or alternative browsers.