Quicbooks desktop and how it determines which email account to use in correspondence.

I have several email addresses that are business and personal. I use Quickbooks and the business email is linked to Quickbooks for sending estimates and all issues related to Quickbooks, my question is; sometimes not always, when I send an invoice or estimate through Quickbooks my personal email address is used as sender? I want this corrected so that my business email is used consistently, how do I correct this issue? I do use Google mail and all of my mail boxes are included in this mail server and it seems that Quickbooks just randomly uses whichever email address it wants when sending correspondence!!??