The default configuration for applicants' Display Names is found under Site > Settings > Content. This will be the default name used for emails and system notifications. 

settings content display name

If a User is only imported as a contact, not a reference, reviewer, administrator, and/or applicant, the default configuration for their Display Name can be found under Site > Settings > Stewardship/Contact Imports, select Configuration tab. 

contact import display name

If the contact's account was first established within Scholarship Management, as a reference, reviewer, administrator, and/or applicant, the Display Name on the existing account will supersede the Stewardship Contact Import settings.