Changing the text in a plugin or theme without editing the plugin or theme files is surprisingly easy IF the plugin or theme has made the text translateable.

Using a plugin like https://wordpress.org/plugins/loco-translate/, ensure the language chosen matches your wordpress language, and choose a location for your files (loco translate helps) that
will be accessed by the plugin or theme (some help with this) and
will not be overwritten by updates – loco translates helps and some plugins/themes help too by offering another lookup location. The recommended custom language file location is /wp-content/languages/.

For more information see http://icalevents.com/3445-an-accent-for-your-website/

Search users text replaced using translation tools – translating english into english!