Preface
After downloading the extension program (FeHelper) and successfully installing it in the Chrome browser, the menu bar does not display its icon.
Solution
The right side of the search bar at the top of the browser usually displays the installed extension icon and an extension management icon.
Click on the puzzle-style icon (Extension Management) on the far right to manage the extensions you have. After you find the corresponding extension, select Fix.
Then you will see the corresponding icon displayed.