YouTube on mobile turns your smartphone into a voice remote for your TV app

YouTube simplifies how you can perform voice searches on your smart TV with a new feature on its Android and iOS apps. All you need to do is press the "Cast" button on your YouTube app and then select the microphone icon that appears. From there, speak into your mobile device to do the voice search on your TV.

YouTube also introduced a new "Who's Watching feature" to make it easier to switch between devices linked to their device. There is also an improved navigation menu on the left side of the screen that displays your favourite pages. If you attempt to cast or open the YouTube on TV app twice in the same day, you'll default to the last account that was signed into. On top of that, the YouTube app on Fire TV now supports Alexa voice control and HDR works on YouTube for the PlayStation 4 and PlayStation 4 Pro.

Source: YouTube Help