@Ari thanks. It worked. I didn't factory reset. I left last firmware but erased all data. After started YouTube was able to sign in and now it works. This is I think not a new version it doesn't play video in music preview. But I need just to show me the video. And it does. Thank you again.

@Ari thank you for prompt reply. I did both the app and the system update. Okay, I will try to restore factory settings. But I think people who make firmware must to exclude all incompatible apps from listing or make the firmware or a hardware compatible with them to prevent confuses. BTW as I remember, I was not able to login to YouTube only after update. It was just didn't react when prompted to log in. Will see.

Just purchased a few days ago Z6 Global version and it has
YouTube play issue. Before update it was not able to even log in. After update I logged in but still YouTube plays only a couple seconds of video and stops. What is the solution? Thanks.