add on domains setup help!!!!!

I have one wp website up and running, with word press in root directory.
I have just added 2 add on domains with separate wp installs on each. all 3 are separate websites. set up the 2 add on domains exactly the same.
so for the first one i enter lets say https://www.newdomainename.com and it goes to the new wp install so i can see wp home page. perfect!. yet the second if i type in https://www.newdomainname2.com just directs me to the people i bought the domain off? i would have to type https://www.origionaldomain.com/newdomainname2/ to enter the site!!! a ah please help very stuck, done a lot of research on this to!

ps all 3 are running on the same data base, i only allowed one on my package.