How to edit text used in multiple places on my site at one time

I’ve been searching for so long for this and really need some help.

I have a short block of text on my site that I use on many different pages, and need to update from time to time. I want to make the edit in one place and see the changes reflected everywhere on my site/

I thought that using shortcode would do this, but in my shortcode plugin I only see how to insert new shortcodes, not how to edit existing ones so that they update in multiple places.

The Ultimate Shortcodes author has not responded to any support questions for over two months.

Thanks for any help!