The default behavior for Reminders and Expirations can be changed but at an Account level and not at a DocuSign User level. So if the change did occur it would impact any new envelopes created by any DocuSign User under the same Account. A DocuSign Admin needs to go to the Admin Console then select "Reminders and Expiration" from the left panel, then make the appropriate changes under "Expirations" section and Save. New envelopes would be affected but this would not change existing envelopes.