...

Once enabled and saved this message will display in all user browsers.

Acknowledging Alerts

...

The alert message appears on top of the content of in the browser to ensure that the message is seen and will be acknowledged. To do so the user will simply click on the OK button and the message will collapse into an alert icon in the upper-right corner. From there the The user can click on it to re-open the message to see what it was for as long as the message remains active and enabled.

Updating the Alert Message

You can can change the message without requiring users to re-acknowledge it or you can save it as a new message to cause the message to be prominently displayed again.

...

If you need to make a minor change to the text that you want users to see if they haven’t already seen the message then simply make your change to the text and press the Save button. Any use user who has already seen your original text will not be required to view the new text.

...