Thanks for your post and welcome to the forums. It's great to have you on board with us
If you updated the app or the OS then you would need to re-register your device. It's easy to do though so don't worry.
Using a PC/Laptop go to anywhere.virginmedia.com > My Profile > Device Settings. Remove the iPhone registration by clicking on the Delete button.
Once you've done this, using the device you are trying to re-register, open up the TV Anywhere app and log in. Try to stream Channel 4 and this should then prompt you to register the device. I have added a device change for you to re-register one of the devices. Follow the prompts on the app and this will register the device for you and streaming will then commence
Let me know how things go.
Kath_F Forum Team
Tech fan? Have you read our Digital life blog yet? Check it out