Every time I turn on the TV I get "Happy Holidays" with snow and it is June. Doesn't this update with each season? I find it very annoying.
Your Roku device/TV may not be updating.
1) Check for updates: Settings/System/System update/Check now
2) Change theme: Settings/Theme/Theme Packs (select one)
3) Disable seasonal themes: Settings/Theme/Seasonal themes=off
What model and model number are shown via Settings > System > About? Perhaps you've got a "Legacy" unit that no longer received updates.