GnuCash Version 2.6.17 No Longer Downloads Quotes

[Robert L. Kief]

Gentlemen:

I'm running Linux Mint 18.1.

I've installed Finance::Quote 1.45 and acquired an ALPHAVANTAGE key.  
I've tested 1.45 by using this string "export 
ALPHAVANTAGE_API_KEY=################" in terminal (using my new key, of 
course).  1.45 returns the proper quote information.  I found the 
"environment" file at "etc/gnucash/environment" and added two lines to 
the bottom of that file:

# ALPHAVANTAGE_API_KEY

ALPHAVANTAGE_API_KEY=################


Replacing "################" with my new key.

I'm unable to download quotes using the GnuCash Price Editor with 
Vanguard as my source.  After a system restart (because it couldn't 
hurt), and changing my source to "T. Rowe Price, US", I am still unable 
to download quotes using the GnuCash Price Editor.  ALPHAVANTAGE isn't 
one of my choices in Security Editor/Source Quote Information.  
Obviously, I'm doing something wrong, but I don't know what.

Any help will certainly be appreciated.

Thank you,

Robert L. Kief