Go to Facebook from your web browser.
Click your profile picture (upper right) and select Settings & privacy.
Select Settings.
Scroll down the left navigation to the Audience and visibility section and select How people find and contact you.
In the main window, find Who can see your friends list? and click the button next to your current selection.
In the pop-up menu, select who you would like to be able to see your Friends list. (Set to ONLY ME /dgp)
If you make a change, click on the Save button.
Click Done on the right to save your settings.