Hi Ka Ho Cheng,
To fully disable the screen saver on your public display PC, you can apply the following Group Policy settings to the OU where those devices are assigned
Path: User Configuration > Administrative Templates > Control Panel > Personalization
Recommended Settings:
Enable screen saver → Disabled
Password protect the screen saver → Disabled
Screen saver timeout → Set to 0 (or leave Not Configured if "Enable screen saver" is disabled)
These settings will prevent the screen saver from activating and override any inherited policies from higher-level GPOs.
If you're managing these devices via Microsoft Intune, you can configure the same settings using Administrative Templates as here: https://learn.microsoft.com/en-us/intune/intune-service/configuration/tutorial-walkthrough-administrative-templates
After applying the policy, you can run the following command on a target machine to verify the settings: gpresult /h report.html
Hope this helps!