How to permanently reset vendor report default value?

[Kris Philo]

I give up!  I only use gnucash about once a month.  I've now spent 
months trying to figure out what i did and how to undo it...

Somehow I seem to have permanently changed the account field for the 
default vendor report from accounts payable to a sub-account of the 
same.  Consequently, every time I run the report, I must edit the report 
options back to AP account.  I don't know what I did to make the 
change.  I can't figure out how to undo it either.  Any help IS greatly 
appreciated!
Kris