A new sign-in reminder may appear on the internet and TV apparatus and a new search bar on Android, which replaces the old search icon. It still looks nothing like the search bar Google uses for all its other programs, but YouTube’s known for sticking for no great reason.
Google’s framing it as a benefit given that signed-in account to get access to features like subscriptions and playlists. Still, I would bet YouTube could much rather have that information associated with funds for more valuable ad targeting.
As for the reminders that are new, we do not understand what those might look, But it is not initially YouTube has insisted on striking its own (random and completely different) route in regards to UI.
YouTube can be marginally altering the recording and uploading attribute is added to the program back in June to include recording speed adjustments and a countdown timer to get multi-segment uploads.