What is a reusable (Global) block, and how do I edit one?

A reusable block is content you write once and place on as many pages as you like. Every page holding it shows the same thing, so changing it in one spot changes it everywhere. You can spot one by its dashed orange outline and its Global tag, both in the block list and on the page itself.

Edit one the same way as anything else: click the text or image right on the page in the visual editor and change it. Because the content belongs to the shared block rather than to this page, the change shows on every page that holds it, and it goes live as soon as you finish typing instead of waiting for Publish (a reusable block has no draft of its own). If you want to change the wording on just one page, swap the reusable block for a normal block there.

Manage the full list under Reusable Blocks in the CMS sidebar, where you can rename one, edit it, or see which pages use it.