Clarification: DuckDuckGo does appear in 'about:addons' > 'Extensions', and it is enabled. However, in 'Preferences' > 'Search' > 'Default Search Engine', DuckDuckGo doesn't appear in the drop-down list. In the actual 'Search' bar, all my search engines appear except for DuckDuckGo.

Did you install the DuckDuckGo Privacy Essentials extension from that DuckDuckGo page as that will install a content blocking extension similar to Enhanced Tracking Protection in Firefox and not a search engine ?

Firefox normally comes with DuckDuckGo as a builtin search engine. You can possibly check that on the "Help -> Troubleshooting Information" (about:support) page. It is possible that Firefox from the Ubuntu software repositories behaves differently and doesn't come with DDG as one of the search engine.

• https://www.mozilla.org/en-US/firefox/all/#product-desktop-release

• https://www.mozilla.org/en-US/firefox/all/#product-desktop-release

Hi cor-el, and Thanks!

Add-ons
Name 	                       Type 	  Version    Enabled
DownThemAll!                   extension  4.2.6      true
DuckDuckGo                     extension  1.0        true
DuckDuckGo Privacy Essentials  extension  2020.12.7  true
Startpage                      extension  1.0        true
Wikipedia (en)                 extension  1.1        true
Yahoo!                         extension  1.0        true
Pioneer Enrollment             extension  2.0.4      false

I downloaded firefox-83.0.tar.bz2 and opened it. But I don't know what to do with the contents because I've only experience with portable apps, but Linux spews installed apps all over the disk, so I don't know where to put the files in the tarball. Can you help? Can I make Firefox portable the way I made Palemoon portable? FYI, Linux is running in a VBox and the portable Palemoon (my prior browser) and it's user-profile is in a virtual USB plugged into the VM. Can I do that with Firefox?

This is the DDG search engine that won't show on about:addons, but should show in "Options/Preferences -> Search":

• DuckDuckGo extension 1.0 true

If you do not see this search engine then click "Restore Defaults".

• https://support.mozilla.org/en-US/kb/change-your-default-search-settings-firefox

This is the DuckDuckGo PE extension that you likely installed from the duckduckgo.com website.

• DuckDuckGo Privacy Essentials extension 2020.12.7 true
• https://addons.mozilla.org/firefox/addon/duckduckgo-for-firefox/

See:

• https://support.mozilla.org/en-US/kb/install-firefox-linux

If you do not see this search engine then click "Restore Defaults".

That worked. It's strange that DDG did not appear when I installed FF, but it does now.

Thanks for your help.