change url without moving anything?

I want to change the domain name of my self-hosted wordpress blog.

My current domain is https://www.fatbeforethin.com and I want to change it to https://www.healthibles.com. I have both domains registered at Godaddy, and my blog is hosted at ipage.com

I’ve been reading for hours, but the only tutorials I’ve found seem to be about moving from a subdirectory to a main directory or changing servers or hosts (I don’t even know if those are the same thing?) If I’ve read something in the forums that pertains to my situation, I’ve been too much of a novice to recognize it. Is there a jargony name for what I’m trying to do?

If someone would be kind enough to give me plain English instructions for doing this, I would be eternally greatful. Thanks