Yes, unfortunately 'inspect element' is just a tool that allows you to look at code, and sometimes test code changes on the fly. It doesn't apply your changes permanently.
I'm not sure where you meant you got this code from, but you should not be looking for the code for the BODY of the page, you're looking for a file called header.php. This file is the code that determines the header for every page of your site, and that is certainly where your
<title> tag is. I really recommend you take a look at this tutorial that explains the files that make up WordPress themes.
As I mentioned before, there are only two ways to access that file:
a) with an administrator account, log into your WordPress dashboard, select Appearance and then Editor from the menu. Once you see a list of template files (index.php, header.php, footer.php, style.css, etc) you can choose header.php and make your change.
b) if you have the ftp login information from your hosting company account, you can use an ftp program to access your server files, download header.php, make your changes, and reupload it. See my instructions in the posts above!