Change "My Account" to "Username" woocommerce sidebar

I want to display for users once logged in instead of the default word My Account I want to display the user's name, I tried this code but it doesnt display anything! it seems it doesn't recognized that variable!$current_userin the file located at: wp-content/themes/themeName/framework/functions/woo-account.php

printf( __( '%s', 'wpdance' ),$current_user->user_lastname);

it was:

printf( __( 'My Account', 'wpdance' ));

Does someone have any suggestion or idea?

Thank you in advanced!

via Chebli Mohamed