Ken Heard wrote:

 
> Between the time of my original post and of your answers I thought of
> another solution, simply create in /usr/bin the following link "ln -s
> firefox-esr iceweasel".  That solution also worked; but your solution
> is better; so I reverted to it once I knew it would work -- although
> with an incomplete understanding of how or why!

In Kontrolcenter you have standard programs, where you can configure web
browser. This setting is saved in the tde config. With the command provided
by Richard, you wrote your setting directly in the config.
Each time tde has to open URL it would use the program configured there.

regards