An app called WatchMaker Premium is what you would need to change faces.
I believe it's like $5 but I cannot remember. Then you can just Google Tag Heuer watch faces and download the .watch file and use WatchMaker to upload to your watch. I'm using a Tag face now. For some reason, I always go back to a Tag. I've used Omega, Rolex, Hublot and many other ones but always went back to Tag.