When you click "extras", you will see settings menu.

I'm not finding an "extras" either. Where is it supposed to be?

Then you disabled it (there is a setting to only make it show up when you press "Alt" button, I have it enabled all the time)

Press left Alt button and it should appear (should look like "File - Edit - View - History - Bookmarks - Extras - Help").

I have "File Edit View History Bookmarks Tools Help" no "Extras" and pressing "Alt" does nothing. Any other suggestions?

Tools it is, sorry, my browser is in german. :P

Under "Tools" I have: Downloads Add-ons Sync Now Web Developer (with a whole bunch of sub-options, not what I'm looking for) Page Info Options Adblock Plus None of these reveal a "settings" "extras" or "Clear Private Data" option. Any other suggestions, please?

Synced tabs should expire automatically after 7 days. If you do not want to wait that long then you can consider to change the password of the Sync account temporarily to reset all stored data.