To change the text on footer, please go to Appearance > ArkaHost - Options > Footer Setting to know which footer you are using.
Then use your FTP client reach to folder /wp-content/themes/arkahost/templates/footer
In here you can see the file for footer you are using.
Example, we are using 'default' footer, so the template for that footer is default.php
Open that file then you can see the snippet for text in here
Just change and save your file.