Which 'From address' do you mean?

In 'Email Service Task' and 'Email Notification', we do have the From address that includes someone's full name in brackets. 

Thanks. How can we do this if we are using variables for From address?

Hi, could you clarify where you want to show the full name (a screenshot preferred) ? Did you mean setting the user’s display name and making it display as the user’s full name in the recipient’s email inbox? 

Or somewhere else on Forms site?

If it's the former, apologies as this feature is not currently supported by Forms, but we will consider it as a feature request.

If it's the latter, could you please specify where you intend to display the full name?