Summarize the following:
Click the Apple logo in the top-left corner of the screen. A drop-down menu will appear. It's in the drop-down menu. Doing so opens the System Preferences window. This option is in the System Preferences window. The Flash Player window will pop up. It's a tab at the top of the Flash Player window. To the right of the "NPAPI Plug-in version" heading, you should see a number; this is the version of Flash Player that you currently have installed. As of October 2018, the most recent version of Adobe Flash is 31.0.0.122. It's on the left side of the window. This will cause the Adobe Flash Player versions page to open in your Mac's default web browser; you should see a table with different browsers and version numbers displayed here. Find your web browser's name in the "Browser" column of the table, then look at the version number to the right of the browser's name. If the version number is higher than the number you found in the Flash Player menu, you can proceed with updating Flash Player.  If the number listed next to your browser's name is identical to the one found in the Flash Player menu, Flash Player does not need to be updated. If you've determined that the newest Adobe Flash version number is higher than your current version of Flash Player, go on to the next step. This should be in the second paragraph that's above the table which should be open on your screen (or go to https://get.adobe.com/flashplayer/).     Restart your browser when asked.

Summary:
Open the Apple menu . Click System Preferences…. Click Flash Player. Click Updates. View the current version number. Click Check Now. Check the version number for your browser. Click the Player Download Center link. Uncheck any boxes in the "Optional offers" column. Click Install now in the lower-right corner. Double-click the downloaded Flash Player installation file. Double-click the Flash Player icon in the window that opens. Follow the on-screen installation prompts.