After releasing iOS 11.4 to the public, Apple today began rolling out watchOS 4.3.1 to all Apple Watch users as a free upgrade. The update fixes an issue where the Apple logo would hang while the Watch booted up for some users.
To install the update on your Apple Watch, navigate to the Watch app on your paired iPhone and tap the “My Watch” tab. From there, go to General > Software Update and you should see the fresh software ready for download. Be sure to place your iPhone on Wi-Fi while downloading this software as it’ll surely gobble up plenty of your data.