The default account option in Windows Live Mail 2012 does not change the e-mail address that new messages will automatically be sent from. Instead, it simply moves the selected account to the top of the folders list.
If this is all that you would like to do, then you can do so using the following steps:
1. Open Windows Live Mail 2012.
2. Locate the account that you wish to use as your default account from the folders list on the left-hand side.
3. Right-click on the account name and select Set as default account.
Note: Windows Mail will automatically send from the the account that you are viewing when you compose a new message. You can change the sending address by clicking on the From drop-down field (located to the right of the To field) and selecting the appropriate account.
