Wife's email shows sent by me. How to change this?

I am the primary account holder.  My wife set up her own email account but when she sends an email, it shows that it's being sent by me, not her.  I also noticed that her email is in a folder under my email, so I can see all of her emails.  Is this normal that her email is a folder under my email?  I would think not!  And, I'm guessing that she set up her email account wrong.  How can this be rectified?  Mainly, she wants her sent emails to show that it's coming from her and not from me.  Thank you for any/all help.