Roku Ultra 4850R Randomly Installing Channels
Roku Ultra 4850R is connected to Samsung QN55Q80D and is randomly installing channels when the TV is turned on. I did not request to add these channels.
I think you're using a screen saver (such as the default one!) that has ads. And if a channel is being advertised in the screen saver, pressing some of the obvious buttons (like OK I think!) means: download the advertised channel. This can get especially confusing, if the TV is turned off and the Roku is still running - and showing a screen saver, but you come in an try to wake everything up and end up telling the screen saver to download the channel, possibly before you even see the screen saver on the TV.
I set my screen saver to be the Roku digital clock, since it has no ads. Other solutions are to be careful and learn which buttons start a download (in a screen saver), or set the screen saver to never activate at all.