Wanted to add this 

© <?php echo '1992 - ' . date('Y') ?>

to my footer but cannot seem to figure out how to do it. 
Tried changing 'Powered' in lang file but didn't work.  Also tried adding to admin>>config>>footer text but that didn't work either.  Any ideas?

Got it to work adding the php into the footer.tpl.php file.  Not sure about future theme updates however.

For each theme change, I recommend duplicating the theme folder and giving it another name.
Select it in the configuration and you will be able to make the desired changes while being able to go back or case!

Then it is the file given by   that must be modified.
Attention to the next update that will undergo a big update of the theme, based on Bootstrap v4.1.1.

Except that there are a few changes that I've made to the core files like auth.php to change the reference to Flatboard in the h4 empty title class.  I guess I could just keep track of my changes but that seems like a lot of redundant work to me.