BenQ EX800ST User Manual page 72

Keyboard
When AMS Service is enabled, this menu will not be accessible by Guest AMS accounts.
Current Displays the current keyboard setting.
Keyboard
Sets the projector's virtual keyboard for inputting text. The available options are
BenQ Keyboard and Android keyboard (AOSP).
Keyboard
Settings
To input Chinese characters, set the language preference to traditional Chinese or simplified
AMS Service
When AMS Service is enabled, this menu will not be accessible by Guest or User AMS accounts.
Select whether to enable or disable the BenQ Account Management System.
72 Operation (under Launcher source)
Chinese, and set the keyboard to BenQ Keyboard.