from PySide6.QtWidgets import QMainWindow, QApplication, QLabel

class MyWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        lbl = QLabel("按钮", self)
        lbl.setGeometry(100,100,200,100)
        lbl.setText("重新设置按钮文字")

if __name__ == '__main__':
    app = QApplication([])
    windows = MyWindow()
    windows.show()
    app.exec()