Hello,
If you want to change just your company name in the copyright text, you can do it in template parameters: Extensions > Templates > "Template Name" > Features > Branding (Joomla 3) or System > Site Template Styles > "Template Name" > Features > Branding (Joomla 4). It's valid only for newer templates, if you have an older template, there's no such option.
If you want to change the copyright text more or have an older template, you should edit the file "/templates/sparky_framework/library/c.php" (open it in any plain text editor and change the copyright paragraph). In the oldest templates, there's a module named Copyright in the module manager where you can change the copyright text.
Regards,
Milos
