3 Answers
+ 2
Perhaps thats because you misclicked something. Once you open your .Py file in python IDLE press f5.
+ 1
I recommend you install the Community version of PyCharm. That's imo the best IDE. There you can write and run all your python programs.
+ 1
IDLE isn't bad for nailing basics, it's simple and effective no needless functions or ui elements, afterwards use pycharm or some other IDE as IDLE has a poor support for many libraries and extra functions will help to manage bigger more complex projects.