Showing “From: [First Name]” instead of the person’s name

Hi,

When I receive an email from someone using my contact form, it shows “From: [First Name]” instead of the person’s name. I have 2 fields in the contact form: first name and last name but the last name doesn’t even appear in the email.

How do I change the settings so that the person’s name shows in the email?

Thank you.