Change the default domain

I purchased a new vps with mautic included. The host set mautic up with all their url details etc by default. I have set up the dns for our domain and change email settings to our domain but every url, link, etc is still the hosts url. As I have never used mautic before this could be only one of a few thing I need to learn but I need help. Any idea how to change this or can I pay someone to fix it for me. Thanks in advance.