As outlined in LRCiv 83.3(d), you must file a notice in each active case.  Please keep in mind the filing of such a notice will not automatically update an attorney’s information in each active case.  Since an attorney’s contact information in CM/ECF is directly linked to their PACER account, it is the responsibility of every attorney to ensure their information is up-to-date by going to https://pacer.uscourts.gov.