Re: Roku TV turned on by itself and tried to download an app... is this normal?
Yes, you can create a PIN to require entry for channel installation. But what you describe I've heard before that someone inadvertently hit the OK button on the remote while the screensaver had something scrolling that can be installed just by pressing the button. Remember that unless you unplug the TV's power, it's actually still on in low power mode.
Dan Roku Stick (3600), Ultra (4640), Ultra (4670), Ultra (4800), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Nvidia Shield, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.