my watch just x and clear all on the screen ?

Hi

That screen is displayed after pressing firmly on the screen when viewing Notification Centre.

Tap on the "x" to dismiss all notifications:

See and respond to notifications

If your Apple Watch does not respond to touchscreen inputs as expected, then the following steps may help:

Remove any screen protector, case or bumper that may be fitted to your Apple Watch.

Clean and dry your Apple Watch, being sure to follow Apple's cleaning instructions:

• Cleaning your Apple Watch - Apple Support
• Important handling information

Restart your Apple Watch, including force restarting it if it cannot be restarted via the normal procedure:

• Restart your Apple Watch - Apple Support

If the issue persists, then I suggest that you contact Apple Support (remote diagnostics and/or mail-in service may be available, if required), make a Genius Bar reservation or visit an Apple Authorised Service Provider for assistance:

• US: Apple Watch Service Answer Center - Apple Support
• Elsewhere: Select your country for Apple Watch service and repair information