How can I add a custom message in the macOS login screen? Our community group has just had three Apple Macs donated to us. Two are laptops with macOS Sierra installed and one is an iMac with macOS High Sierra installed.

I’ve been asked to add a custom message to the login screen acknowledging the donation, but I am not familiar with Apple Macs. It only needs to be a simple message like:


  This Mac was kindly donated by X.


Is there a way of doing this without having to use any 3rd party software? I would need some very clear steps.
This can be done without 3rd party app. Simply open System Preferences.app -> Security &amp; Privacy -> Show message when the screen is locked. Here are the steps:


Open "System Preferences" (located in you applications folder)
Select "Security &amp; Privacy"
Unlock the padlock
Set the lock message