Change "request" to "case"

Hi there,

We are about to release our Zendesk help center, but we need to change the word "request" to "case" everywhere. How can we do this?

I tried all the scripts provided in https://support.zendesk.com/hc/en-us/community/posts/4409507233562-Customizing-My-Activities, but none of them worked. I notice the post is five years old, so perhaps that is why. 

Any help is appreciated. Thank you.