On which screens are you seeing this?
Which box do you have as the issue could vary between these.
If the advice from @Mandisa-TT does not work, I'd suggest firstly trying another HDMI on your TV, changing the HDMI cable (if you have a spare),and if that doesn't work doing a factory reset as the setup should be automatic and be able to read the optimum output form your TV.
Re the HDMI cable, if it's the Hub or 4k box and your TV is rated as 4k, then you should use a 4k rated cable. The one's provided with the Hub or 4k boxes should be rated as such.
If it doesn't work, please confirm the box, the screens affected, and take some photos so we can see the issue.
Also could you let us know the make and model of your TV
It might also be worth checking your TV settings to see if there are an variables on individual HDMI ports that may affect connected devices.
Please remember to mark Solved Posts with Best Answer. Doing so helps other customers and saves TalkTalk's Support Team time by only looking at unsolved topics. Thanks, Steve (a fellow customer).
