import sys
from PySide2 import QtCore, QtWidgets, QtGui
import datetime

class MyWidget(QtWidgets.QWidget):
    def __init__(self):
        QtWidgets.QWidget.__init__(self)


        self.button = QtWidgets.QPushButton("Click me!")
        self.text = QtWidgets.QLabel("Change time")
        self.text.setAlignment(QtCore.Qt.AlignCenter)

        self.layout = QtWidgets.QVBoxLayout()
        self.layout.addWidget(self.text)
        self.layout.addWidget(self.button)
        self.setLayout(self.layout)

        self.button.clicked.connect(self.changetime)



    def changetime(self):
        i = "17:48:00"
        print (i)
        format1 = "%H:%M:%S"
        date = datetime.datetime.strptime(str(i), format1)
        date = date.strftime("%-I:%M %p")
        date = str(date)
        print("check {}".format(date))
        #print("Convert {}".format(date))
        #return date
        self.text.setText(date)



if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)

    widget = MyWidget()
    widget.show()

    sys.exit(app.exec_())