The simplest way is to change it in Settings > General > Email Address.
Then there are the alternative methods which will depend on how you have your site set up. If you’re using an email plugin (like Mailgun, Sendgrid, Postman, or any of the several SMTP ones), they’ll give you the option to change it as well.
If none of the above helps you, then you can hook into the headers of bbpnns to set your own From address.
The filter name is bbpnns_extra_headers and it takes 4 parameters: $headers, $recipients, $subject, $body.