Hi Wigsey73 👋 welcome to the community, thank you for posting!
Sorry to hear you need a hand with your TV go devices. There are full instructions on how to register and change devices on the help page here 👉 How to use Virgin TV Go app | Virgin Media Help in the section titled 'How to sign in and register a device on Virgin TV Go'.
Once registered, the devices need to keep the cookies enabled or this may reset the device again. You can read more about this in the community thread here 👉 TV Go registered devices - Virgin Media Community - 4457311
If you have maxed out the number of changes available to you this month sadly you need to wait for the allowance to reset again.
Let us know if you need any further help! Wishing you all the best. 🌞