How to make links in Tbird open specific version of Firefox

[DontEatThat]

I have two versions of FF installed: One current updated version and an old version.
When I click on a link within a Thunderbird email, it opens the old FF version, even though the old version is NOT set as the default. The updated FF version IS set as the default.

How can I make TB links open the default/updated FF version?
Thanks to anyone who has a solution!

The two versions are in different profiles/folders and they can be opened at the same time.

I wasn't sure whether this question should be in FF forum or here!
[I use the older FF version only to play a particular java game with a friend.]

[DanRaisch]

When you click on a link in Thunderbird it sends a call to the operating system to launch the default browser. See this link to set the default browser -- http://kb.mozillazine.org/Setting_Your_Default_Browser Note that Windows can be stubborn about switching default applications.

[tanstaafl]

See http://kb.mozillazine.org/Changing_the_ ... hunderbird if you want to use a specific browser, rather than the systems default browser.