After the a firmware update, where google assistant was introduced, the voice search funcationallity has been downgraded. 

Before the update:
- Direct and comfortable search within apps possible by shortly pressing the voice button on the remote control when app is launched. (eg. Youtube, Spotify etc.)

- While in an app, possibile to long-hold the voice button and open a general (global) voice search

After the update:

- When an app is launched, it doesn't matter whenever you shortly press the voice search button or hold it, it always starts the "google assistant" general (global) voice search. While this voice search can search in all apps, the results are not as detailed as when searching in a specific app. For example, when you search something directly in the spotify app, you get sorted results by songs, albums, playlist etc. 

- Direct voice search in apps not possible anymore by using remote control