Google has been adding in plenty of changes and tweaks to YouTube across numerous updates, some of which have been behind the scenes or more under the hood changes like the support for 360 degree videos and 60fps videos and live streams. In the latest update though, Google brings a more visually noticeable change with a fairly substantial redesign of the UI aimed at making navigation of your videos and channel subscriptions easier. They've also added in some new tools and things to make the app more useful to those who record videos and upload them using their smartphone or tablet. In addition, these changes aren't just for the Android version of the mobile app, but also for the iOS version as well as the YouTube mobile web page.
Aside from the new UI, Google has also added video editing tools into the app to make it easier to get things just right. The new app lets you upload your footage after recording just like before, but you can now also trim your footage down as well as add filters to the video if you want to. The editing tools also allow you to add music before you finish up and upload to your channel, so there's no longer a need to get things done on the PC. The changes take a little getting used to, but things definitely should feel much more streamlined.