Change symbol/text of a button in a btnmatrix widget when pressed

How to change the symbol or text (label) in a button in lv_btnmatrix

There is a lv_btnmatrix_get_btn_text(btnm, btn_id) what I to know if there is a way to change the buttons label i.e. like a lv_btnmatrix_set_btn_text(btnm, btn_id);

Or do I have to create a grid of buttons and not use the btnmatrix widget

Waveshare ESP32 S3 touch 4.3" Using lvgl v8, as I am not sure if the waveshare lvgl_port_v8 is compatible with v9.