How to realign database from subdomain to main

My main site is connected to one of my subdomains making it impossible to change the content on one without affecting the other. My hosting company (Fatcow.com) said this happened because the database was pointing to the subdomain (don’t know why) when I installed wordpress. The tech suggested I realign the database but I’m new to this and it just sounds like spanish to me. Can someone please help a newbie out?