Each Admin user has the ability to change the default values for From Email and From Label so that when they create new emails, those defaults are used.
Admin Permissions Required
Go to the Admin section.
Click Email.
Enter the default values you want for From Email and From Label then click Save Changes.
The change is only applicable to you and not to other Marketo users.
Good job! Every time you create a new email the default values you set will be used.