Hi @TomGo,
Welcome to the Roku Community!
Thanks for reaching out about this issue. We'd be glad to assist you. To confirm, is this an issue when you're accessing an app, or does it happen even when you're on the home screen?
For troubleshooting you may begin with a system reset by navigating to Settings > System > Power > System restart. Then you can try to follow up on how to adjust ambient light sensing on your Roku TV system.
You can also check for additional information on how to improve image quality using picture modes on your Roku TV system.
Let us know if the suggested steps work.
Thanks,
Rey
ERey.
Roku Community Moderator
