The notes pane is until you tap or click the notes button on the status bar to open the pane.

Hey there!

In PowerPoint, the notes pane will remain hidden until you click the Notes button on the very bottom of the window. The button is near the presentation view options where you can also sort your slides, make comments on the presentation, adjust the zoom options, or enter the presentation. 

Hope this helped you out! :-)

It really depends on your memory. if you have a great one then probably. i have done it before personally and it’s stuck with me since i was 6. but if you have a bad one then it might stay for a while but i wouldn’t say permanently