After the latest YouTube update this app does not work on Roku anymore. I removed the app and then reinstalled it and it did work once again. However I've had to do this four times now. It always stops working after a few days. This is unacceptable and as far as I'm concerned the app is broken. Having to reinstall it every few days is not a solution. This YouTube app is more trouble than it's worth.
When you reinstall an app, you need to make sure you RESTART (Settings/System/System restart/Restart) after removing the app, and before reinstalling it:
1) Remove the app (Highlight the app, press the Options (*) button on the remote, then Remove)
2) RESTART the Roku (Settings/System/System restart/Restart) <-- MUST DO THIS HERE!!!
3) Re-install the app
Otherwise, settings/cached data associated with the app are left behind and it wont be a clean re-install.
As far as the YT app itself goes, you need to direct all those issues to Google, since they develop it.