How do I change the from address or name of a campaign?
Scenario A: You have not yet created your campaign
First, click on "Mail Accounts" in the menu:
To just edit the "From name" of your emails
Click edit next to the mail account:
Make your edits and click Save:
To send from another email address:
Follow detailed instructions here to add an alias, or just click the "+" button to connect another Google account.
Selecting a mail account when creating your campaign
When you are creating your campaign you can go to the "Start" step and choose any of your mail accounts or aliases, or you can connect a new Google account:
Scenario B: You're updating an existing campaign