Here's what worked in the past, copied from /questions/967426#answer-465453

Doh! Here's the easy way. Go to the following page, then click the icon at the left end of the search bar, and look for Add "Answers.com" on the drop-down menu.

http://www.answers.com/main/firefox_plugins.jsp

Does that work?

I tried it myself, by going to http://www.answers.com/main/firefox_plugins.jsp and clicking on the "magnifying glass" icon in the Search bar, and then clicking on Add "Answers.com" (see the image, below).

For more help see the article Search bar - add, change and manage search engines on Firefox under "Add a search engine".

Thank You seems too inadequate to express my deep thanks. This has been bugging me for awhile.

I tried the 2nd method you suggested and it worked great.

The Search bar article you referenced is useless for answers.com because it is not one of the hundreds of search engines listed.

Thank you again and I have copied and saved the info you sent so I'll never have to bug the community again with this one.

You'll welcome. I'll mark this question "solved".