By editing your approval or decline message you are changing the email that members receive when you manage your requests by pressing the Approve and Decline buttons.
You can create a default message or customize by title.
Please note that when you edit the Approval/Decline default email, the new edited version becomes the default that is used for all future approvals or declines (until you edit it again).
The default Approval/Decline emails are across all members and all titles that do not have a customized message.
You can add a title-specific Approval/Decline email from the title record which will only send to those members you approve or decline for a certain title. If there is no title-specific email set, the member will receive your default email.
Here is some suggested template language for approval and decline emails.