You can't do that anymore. In Firefox 4 you can only enable or disable the History. The pref that previously defined the number of days are no longer used.

The prefs browser.history_expire_days and browser.history_expire_days_min are removed in Firefox 4.0 versions and replaced with a single places.history.enabled pref to remember history or disable the history.

See http://blog.bonardo.net/2010/01/20/places-got-async-expiration

Thanks for the answers cor-el. I'm unsure if I like history saved that way. I'll read the article from the blog you provided. Good information!

argh!!! so annoying! i was in the habit of manually inspecting my history and deleting a few days worth of links when it got full. now i have no choice but to rely on this new automatic process or clear the entire history!

This is very frustrating!!! :( I don't like that Mozilla has taken away our choice and preference on this issue. Keeping history should be fully customizable to individual preferences!

I will probably be reverting back to the old version of Firefox because of this and a few other annoying "updates" in version 4.

I am very unhappy that this change has been made, that we cannot set how many days to keep history,. This is exactly what I have always wanted, and what I want to continue to do. It should not have been taken out of a 'version' of a product at all because many existing users will or may want it. I ask you to return the facility as I think you will find many others want it back too.

I have read the blog referred to where the programmer appears not to realise that he removed afeature that is still required. I never thought of number of days as any compromise, it is exactly what I want, not somethiung based on memory or "as much as possible" or "as little as possible", I need number of days.

I have also noticed an other funy thing that I bet is related. When I browse a directory, which will have a lot of links, one for each file, then every so often some sort of refresh occurs and it forgets my recent few minutes history and all my purple links turn blue again. I bet this is part of the refresh described in the blog mentionedin this thread. This is no good, I need to see where I have been. I need to se my used links stay blue, obviously.

I got my computer science degree in 1979 (for my sins, don't do it, I was young and foolish!) and I have been in the computer industry ever since, in manufacturing computers and in systems. This is a cockup if ever I saw one (sorry in advance, but that is how it is). I beg you to put this right.

This is very annoying and ever since this change I get lag whenever I switch browser tabs... same problem I had in older versions of Firefox without this setting.

Please bring this setting back!

I think we can still set our History. Open a new tab, type "about:config" and filter for "history". The "browser.history_expire_days.mirror" setting says 180 for me, which is consistent with what I know about the History (that it's kept for 6 months). I didn't try modifying the setting since it is to my satisfaction.

But anyway... What is going on at the FF team? Releases every 6 weeks, crashes, bugs, talk of removal of version numbers and tons of other removals, such as this history thing. I just came to FireFox this January from Opera because FF offered more features. So you try to find new users by dumbing down the browser?

The prefs browser.history_expire_days and browser.history_expire_days_min are removed in Firefox 4+ versions and replaced with a single places.history.enabled pref to remember history or disable the history.
If you still have them then you can right-click them on the about:config and reset them to the default values.
They will be removed on the next start from the about:config page.

You can look at:

• Expire history by days: https://addons.mozilla.org/en-US/firefox/addon/expire-history-by-days/