Why does my Firefox browser only display the history of the last four months without deleting it. How do I find the history of Firefox four months ago? When I clicked on Manage History, I found a recovery option. But when I click the time period I want to restore, it shows that the operation will overwrite my current bookmark with the backup bookmark. When I click Confirm, I did not find the overwritten bookmark. I feel confused. Can you help me? Thank you.