Please confirm you are using latest version of Panagea theme.
Latest version is 1.0.9
And then you can find the text in /inc/funtions/template-functions.php file.
wp_localize_script( 'panagea_script_main', 'copyright_text', esc_html__( '© 2018 Panagea', 'panagea' ) );
Please change the text in it.
Another way is following.
Please confirm you are using latest version.
And replace /languages/panagea.pot file with attachment.
And then translate the text using language file. Panagea theme is translation ready. Please check https://panagea.c-themes.com/documentation/#translation