您正在保存vallues但你必须恢复他们，你的活动开始是这样的：

You are saving vallues but you have to restore them you your activity is started like this :

SharedPreferences prefs = getSharedPreferences("syllabus", 0);
checkbox1.setChecked(prefs.getBoolean("cbx1_ischecked" ,false));
checkbox2.setChecked(prefs.getBoolean("cbx2_ischecked" ,false));