To change the "From" name or "Reply to" values for your email campaign, as well as other contact settings, you should click the drop down mail/envelop icon on the main page of your campaign.
From here you can change the "From" name "Reply to," CC, and BCC and more advanced settings to improve your email deliverability.
The default for the "From" fields are your store name and email provided in your account settings. If you change the settings here, they will become the default for all campaigns created afterwards. If you would like to update all of your existing campaigns with new "From" and "Reply to" emails, make sure to check "Apply now to all campaigns" before clicking "Save".
For more questions, contact firstname.lastname@example.org