Edit an SLA
Analyzing your SLAs can help you pinpoint the most effective ones and the ones that may need to be changed. You can edit your SLAs at any time.
After an SLA instance is applied to an organization or contact, it cannot be changed. When you edit an SLA, the changes will not affect the instances of the SLA that have already been applied to organizations or contacts. Changes will affect only future instances of the SLA applied to a contact or organization. For your reference, a view-only version of the SLA instance is archived. See View Disabled SLA Instances.
Results:
The next time you assign this SLA to contacts and organizations, the changes will apply to all instances of the SLA.