1 Answer

.. you could inadvertently be striking the wrong keys ... ctrl then + or - will increase or decrease the size of the font etcetera...or you might be left cliking and scrolling nearest the page edges and again inadvertently decreasing the size of the page that way... in which case, cut it out or just do the reverse to enlarge the screen, you'll see an arrow that points in both directions which is what you will clik and drag with ...

a third possibility is that you are again, inadvertently mind you,striking the page icon on the top right screen beside the x which simply decreases page size by an inch or two and when you clik on it again it returns to normal ...

 good luck ...