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.
You will now be able to change the "From" name Reply To, CC and BCC and more advanced settings to improve your email deliverability.
The default for the "From" name will be your store name and the 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