How to update the short description text of my website on Google ?

The update is automatic.

It is often the content of the meta description. So all you have to do is changing it and wait.

If the META Description tag is not relevant enough or not filled enough, search engines will then choose another fragment of the text in the source code.

In order to speed up the process, you can try to obtain new links to the page that was changed.

SEOSoftware Oseox Monitoring