Firefox has a feature which lets you restore recently closed tabs. This comes in handy when you accidentally close tabs or if your browser crashed. By default Firefox keeps track of your 10 most recently closed tabs.
If you keep opening links in new tabs, then 10 tabs in your history won’t be enough to fully recover should an accident happen. So here’s how you can increase the tab count.
Open Firefox configuration page by typing in about:config into the address bar. If it’s the first time you are accessing this page, click the “I’ll be careful, I promise!” button to continue.
Next paste the following into the Filter box:
browser.sessionstore.max_tabs_undo
You can see the default value set to 10. To modify it, double-click on the preference and enter in a new value. For example, to keep history of 20 tabs, enter 20 as value.
You can set value as any number you want, however Firefox has another setting that makes it max out at 50. If you think you need more, here’s how you can change that as well.
Enter the following in the Filter box:
browser.sessionhistory.max_entries
See the value 50 ? Change it to anything you want.
That’s it! Now your closed tab history can be as big as you set it to be.