diff --git a/doc/user_guide/en/tutorial-example3.adoc b/doc/user_guide/en/tutorial-example3.adoc
index 51bd36412..a5af8902c 100644
--- a/doc/user_guide/en/tutorial-example3.adoc
+++ b/doc/user_guide/en/tutorial-example3.adoc
@@ -67,7 +67,8 @@ station.
 
 ** You can modify the double-click behavior by holding down the
 *Shift* key to move only the Tx frequency or the *Ctrl* key to move
-both Rx and Tx frequencies.
+both Rx and Tx frequencies. (On a Mac computer, use the *command* key
+instead of *Ctrl*). 
 
 ** In addition, if *Double-click on call sets Tx enable* is checked on the 
 *Settings | General* tab then *Enable Tx* will be activated