Several years ago Apple's operating system introduced a feature called Natural Scrolling.  With natural scrolling, a trackpad or a mouse wheel no longer follows the direction of the scrollbars. Rather, the pointer responds as if your finger were touching the screen.  This is identical to the behavior seen when swiping up or down on a webpage on an iPad or iPhone.  

Natural scrolling will be enabled by default on your computers.  You can easily disable this feature if you would like to return to the scrolling that you have been used to over the years.  The choice is yours.

To Enable/Disable natural scrolling:

1.  Click the apple in the upper left corner of your computer and select "System Preferences"

2.  In the Systems Preferences window, click "Trackpad".

3.  Next, select the middle section title "Scroll & Zoom".  The option to enable/disable natural scrolling is at the top.  If you hover the mouse over that section, you get a video preview of the scrolling behavior when natural scrolling is both enabled or disabled.  Decide which option your prefer.