If the section is a prefab
The most efficient way to share content across pages is with a prefab — a saved section that all pages reference. If the section was added as a prefab, updating it is straightforward:Click to open the prefab editor. Make your changes — update the text, swap images, change colours, whatever you need.
If each page has its own copy of the section
If the section was built individually on each page (or inserted from a template, which creates a one-off copy), there is no automatic sync. You will need to update each page separately. To avoid this in future, move the shared content into a prefab:Open each page, delete the existing copy of the section, then click Add section → Prefab and select your new prefab in its place.