Can I add the following clarifications for anyone who may need the same query resolved in the future.
The relevant file is frontend-jobs.php and the phrase to be altered can be found on line 305.
To edit the file you will need to use an FTP client to retrieve the file from your website server (I used FileZilla).
Copy the file(adding the term - original to the file name. You can now edit frontend-jobs.php with the confidence of knowing that if it all goes bad there is a backup!
Editing is simply a matter of using a suitable PHP editor (I used Notepad++).
Once edited save the file and then FTP it back onto the server.