'send from' account won't change ?

[muddy123]

i changed my default 'send from' account in outlook 2010 (windows/7, 64bit); when i answer an ad in craigslist, it sets up an outgoing email, but with my former default 'send from account' ; i can manually change the 'send from' email address to my new default ok; i'm trying to avoid manually changinig it every time; i thought of deleting my old default account from outlook, but i'm not quite ready to do that , as this is a minor problem; can i somehow suspend my old account with out deleting it ? thanks