How to change the website's name/attribution that also reflects the change on Google search?

I am trying to change my website's appearance on google search, particularly the website title or attribution (pointed by red arrow).

I want to change it so that instead of saying gamsatideasbank.com, it says GAMSATIdeasBank or something like that. I have looked up many articles on how to do this, but all of them are for changing the website name which is already correct (Ultimate GAMSAT Section 2 Ideas Bank). So how do I change the part in the picture with the red arrow?

Cheers!