Those are not cookies. Those items are saved by Windows.

To clear that list, you need to uncheck and then recheck the Store and display recently opened items in the Start menu and the taskbar in the Windows setting.

You also can manage the categories of data Firefox puts on the Jump List as follows:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button accepting the risk.

(2) In the search box above the list, type or paste taskb and pause while the list is filtered

** To disable listing Recent pages on the jump list: **

(3) If the browser.taskbar.lists.recent.enabled preference is bolded and "modified" to true, double-click it to restore the default value of false

** It appears you might already have made this change: **

(4) To disable listing frequently visited pages, double-click the browser.taskbar.lists.frequent.enabled preference to switch the value from true to false

Does that work?

Hi,

I couldn't find a way to solve it so I uninstalled Firefox and reinstalled.

However, this doesn't work either.

I'm going to try your method, then get back to you.

Nope, doesn't work at all.

"browser.taskbar.lists.recent.enabled" is set to false.

Attached image.

Firefox is just routinely storing a list of websites I visited in some unknown list.

Wow, that's hard to explain.

I have Recent documents on jump lists for Acrobat, MS Word, Notepad, and Notepad++. Pretty much the only one that doesn't have Recent for me is Firefox.

I haven't restarted to get 69.0.2, so I'll do that now and see whether anything changes.

Well, I googled what Wesley Branton said and cleared all the files in

   %APPDATA%\Microsoft\Windows\Recent\AutomaticDestinations

I've also turned off the Jump lists and it seems to have worked.