Apple TV Streaming Channel Screen Size Too Large

I have loaded Apple TV on my Samsung Smart TV using a Roku device, going to Streaming Channels and selecting it! After signing in and have it download, I see the screen size is too large to view the content in its entirety. I cannot see what is at the top, the bottom and thus the movie boxes are not aligned in order to know where to click. Supposedly, once the App appears, one should be able to select settings at the top. Can’t see it to invoke. How does one reduce the screen size to be able to see all of its content? First time ever encountering this problem!