You can make Firefox 4 look and behave similar to Firefox 3.6.

For details of how to do that see http://redherring2.wordpress.com/2011/01/17/firefox-4-restoring-firefox-3-ui

To downgrade to Firefox 3.6.* you can uninstall Firefox 4, but do not select the option to "Remove my Firefox personal data". If you select that option it will delete your bookmarks, passwords and other user data.

You can then install Firefox 3.6.* available from http://www.mozilla.com - it will automatically use your current bookmarks, passwords etc.

To avoid possible problems with downgrading, I recommend going to your profile folder and deleting the following files if they exist - extensions.cache, extensions.rdf, extensions.ini, extensions.sqlite and localstore.rdf. Deleting these files will force Firefox to rebuild the list of installed extensions, checking their compatibility, and reset toolbar customizations.

For details of how to find your profile folder see https://support.mozilla.com/kb/Profiles

Firefox 4.0 introduces itself very attractively but it is instead a quantum leap ended up into manure: HOW DO i OPEN A NEW TAB? That is the most common action. Where are delicious bookmarks? I do not give any damn about other bookmarks. Where's my web developer toolbar? Can't find it. Video about easier user interface? Had not any human like me in your groups, unfortunately.

oliopepesale:

Open a new tab

1. As always you can press Ctrl+T
2. Using the Firefox button (Firefox 4): click Firefox button > New Tab
3. Using Menu Bar: click File > New Tab
4. If you have the Ask Toolbar installed, un-install it as it is causing a problem with opening new tabs
   • http://about.ask.com/apn/toolbar/docs/default/faq/en/ie/index.html#na4
   • http://support.mozilla.com/en-US/kb/Uninstalling+add-ons
   • http://support.mozilla.com/en-US/kb/Cannot%20uninstall%20an%20add-on
5. Otherwise:
   • You may need to try Firefox Safe Mode
     • You may need to use Safe Mode to locate the problem: ***See: http://kb.mozillazine.org/Safe_Mode
       • Firefox 4 users, hold the Shift key while clicking the Firefox 4 desktop icon to enter Safe Mode.
       • Firefox Safe Mode is a diagnostic mode that disables Extensions and some other features of Firefox.
         • In Firefox 4, Safe Mode also disables Plugins and Hardware Acceleration.
         • If you are using a theme, switch to the DEFAULT theme: Tools > Add-ons > Themes before starting Safe Mode (In Firefox 4, Tools > Add-ons > Appearance). See: http://support.mozilla.com/en-US/kb/Using%20themes%20with%20Firefox#w_managing-themes-and-personas
         • When entering Safe Mode, do not check any items on the entry window, just click "Continue in Safe Mode".
         • Test to see if the problem you are experiencing is corrected.
       • If the problem does not occur in Safe-mode then disable all of your Extensions and Plug-ins and then try to find which is causing it
         1. by enabling one at a time until the problem reappears.
         2. You can also enable a few at a time (3-5), keeping track of what you just re-enabled to see if the problem re-occurs; this will help narrow down the possibilities if you have a large number of add-ons.
         3. You MUST close and restart Firefox after EACH change via File > Restart Firefox (on Mac: Firefox > Quit).
         4. You can use "Disable all add-ons" on the Safe Mode start window.
     • See the following for more information
       • http://support.mozilla.com/en-US/kb/Troubleshooting+extensions+and+themes
       • http://support.mozilla.com/en-US/kb/Troubleshooting+plugins
       • http://support.mozilla.com/en-US/kb/Basic+Troubleshooting

Delicious Bookmarks

1. The developer of Delicious Bookmarks has not updated the Extension; that is the developer's responsibility
   • See:
     • http://support.delicious.com/forum/comments.php?DiscussionID=5691&page=1#Item_0
       • You can join and post in that forum: http://support.delicious.com/forum/index.php?CategoryID=14
     • You can try the steps here: http://www.howtogeek.com/howto/21478/how-to-bypass-firefox-4.0-betas-incompatible-add-on-error-and-install-extensions-anyway/
     • You can try installing Add-on Compatibility Reporter: https://addons.mozilla.org/en-US/firefox/addon/15003

Web Developer Toolbar

1. Are you talking about this: https://addons.mozilla.org/en-US/firefox/addon/web-developer/
   • If so, have you updated to the Firefox 4 compatible version?
2. Have you looked at: click Firefox button > Web Developer ?

Follow TonyE's instructions on how to delete some folders from your personal profile (click 'Help' then 'Troubleshooting Information...' then under Application Basics, click on 'Open Containing Folder').

Go to the Control Panel and uninstall Firefox 4. Do not put a checkmark in the box if you want to keep your personal settings.

Go here and download Firefox 3.6.16: http://www.mozilla.com/en-US/firefox/all-older.html

I see a lot of people talking about how to make 4 LOOK like 3.6..big deal...I want it to BEHAVE like 3.6...like not taking up 2 gigs of RAM if I leave it open more than 90 minutes.

Thanks for the instructions. I'm switching back. The version 4 'forgets' everything. Passwords and custom settings. For example, I had to go back in my privacy settings to find my password for this site since auto fill in FF4 didn't log me in. To my surprise, the password and login info wasn't there.

Buttons I add to the toolbar disappear after the browser is closed (cut, paste etc). No tab button. V4 is terrible compared to 3.6

I need help aswell :3