With this plugin you do not have to modify neither template's nor Joomla!'s core files. Install it, configure it and you are ready!
So far, the most common way to change the generator meta tag is to modify the 'index.php' file of your current template. If you change your template, then you will have to modify the new 'index.php' file again. TJ Set Generator Tag does not depend on templates nor it modifies any of their files. Feel free to change as many templates as you want. The generator meta tag will remain intact.
Another way to change the generator meta tag is to modify a Joomla!'s core file. But by doing so you are risking of losing the modification when you upgrade Joomla! to a newer version. No more worries with TJ Set Generator Tag.
A tip for you:
If you leave the generator tag field empty, then no generator meta tag will be shown in your site's source code!
TJ Set Generator Tag was previously known as "Set Generator Tag". It is developed and maintained by the same team as before.
I am glad that everything went fine! If you have any comments or suggestions for future releases do not hesitate to contact me.