If changes must be made to the HSI, they should be salient.
Additional Information:
Drawing the user's attention to characteristics that have changed can help them to adapt their skills. For example, injecting a single new word into a message is not recommended. Adding the word 'not' to a question, such as "Do you want to save these settings?" will change the meaning of the message. However, it may not be detected by the user until an error occurs. Many actions become automatic as users become skilled in using the interface. If HSI changes are obvious, users may be able to block their automatic responses and develop new ones.