Once a direct invitation is sent through SignUp, the Message text is saved and stored for all future invitations. To change the message, please follow this process:
1) Start by going to the Invite tab of your SignUp's Organizer view. (Login and in the My SignUps menu on your Dashboard, click the SignUp Title to open your Organizer view).
2) Select Send an Email through SignUp then make the changes in the Message window and send at least one invitation. If you do not need to send an invitation to a Participant at this time, just enter your email address to send the invitation to yourself. This will complete the process and store your new message.
Note: To send a personal message or update to participants previously invited to your SignUp, don't us the Invite tab, instead, go to the Message tab in the menu bar. You can then customize a message and choose who to send to (by SignUp status, date, or even shift). A personal link to your SignUp will be automatically included in the message. Learn how here