Q: I have lost Time Machine backups after latest backup something to do with security error or authentication.  now it only goes back to march 2016  ,previously it went back to 2012. It is the same on both backup disc, one locally attached and the other

Q: I have lost Time Machine backups after latest backup something to do with security error or authentication.  now it only goes ... I have lost Time Machine backups after latest backup something to do with security error or authentication.  now it only goes back to march 2016  ,previously it went back to 2012. It is the same on both backup disc, one locally attached and the other more