The brush function is not turned on.

Open WPS on your phone, open PPT, click on the ink writing tool I pen tab option, click on the brush, and turn on the green after disabling ink, you cannot use the brush function. You need to turn on the green after using your finger. Use a paintbrush.

WPS means text editing system in Chinese and is an office software from Kingsoft Software Company. It integrates editing and printing, has rich full-screen editing functions, and also provides various control output formats and printing functions, making the printed documents beautiful and standardized.