That has already been done. Maybe I should have said that I am also new to
Thunderbird and explained my situation a little better...

When I click on a link that is a text or a you tube link Firefox opens it and
starts to play the movie before I can click on the Firefox tab or hit ALT-TAB
and get Firefox to pull up. Windows used to bring Firefox up over the email
program but Ubuntu doesn't do that. Now, I know it's probably not Ubuntu but
rather Thunderbird but I couldn't find anything in FAQ's.