I've never heard of a Youview box asking for a BT TV account unless you're trying to access the BT's subscription channels , either live or as recordings.
The BT TV app on iOS and Android phones used to but doesn't now.
Thanks. Do you think I need to start again with a Freeview recorder? Pity to lose old recordings
Not yet as I'm still confused as to what is actually happening or not happening.
So you connect the box to the TV via the HDMI cable, you connect the aerial into the Youview box aerial in socket & then connect the aerial out to the TV's aerial in.
Have you connected the box to the internet at this stage?
So you then turn the TV on & the Youview box on and switch the TV's input to the appropriate HDMI input.
What happens then?