Exchange 2013 domain name

Hi,

I recently installed Exchange 2013 on premise on my domain-controller.

I'm new to exchange management and I want the mailbox names to be "name@company.se" but when I try to make a new mailbox it automatically decides to go with "name@company.local" which is the local domain name.
Can I change the name and if so how do I make this change? Did I do something wrong during the installation progress?

Thanks