How to mass override natural account segment after accounting?

The Business has mainly two types of projects SAAS and IDS. The natural account segment of both the projects are 160180 which belongs to historical data. The user requirement is to mass update the Historical Data's Natural account segment 160180 with 160181 for SAAS Projects and 160135 for IDS Projects. I have successfully tested for override the Natural accounts for few transactions. The process should have to apply for Bulk of transaction where we have to update SAAS project account with 160181 and IDS project account with 160135.