h1 and author name, updated date should be in the center

Hi,

Can you link us to the site in question?

Also, On what part are you trying to implement this? (blog list? single posts page?)

https://www.masteryblogging.com/a2-hosting-reviews/

Single post

You can try adding this CSS.

body.single header.entry-header {
    text-align: center;
}

not working

Strange. It should work. As shown here: https://share.getcloudapp.com/eDuPYXD8

You can try this instead.

/*For entry-title*/
body.single .entry-title, .entry-meta {
    text-align: center;
}

This is how it'll look like if applied properly: https://share.getcloudapp.com/yAulW1NG

It is not working in the LIVE preview.

Elvin's CSS should work but I'm not seeing it being added.

Can you double check?