The copyright link is originally removed because clicking the link would send Invision Power the referral for your site, and they would know you were using nulled software. It's possible to put it back in templates, though it's advised to not.
Try replacing default_thumb.png as well.
If it still hasn't changed you will have "Allow users to use Gravatars" set as "Yes"
You will need to set this as "No"
Go to: System > System Settings > Members > User Profiles > Scroll down to "Allow users to use Gravatars"
and set it to "No" Like the image below.
Thanks,
Matt