Question

By clicking which button one can return the windows to its previous size

Answer 1

The maximise button

On the top extreme right corner you will see three buttons ,the middle one will be the maximise button .

Answer 2

Returning to previous window size is not at all a matter.

You can use the MAXIMIZE button which is on the top extreme right corner.

You will also find three buttons, the middle one will be maximize button.

Thus, by clicking here, you can return to the previous window size.

In addition to it, you can also click alt+tab as a shortcut to go back to the previous window size.