There is no built in functionality that will change the password expiration interval globally for users that already exist.
It could be done programatically.
1. Run a TSSCFILE TSS LIST(ACIDS) DATA(BASIC) to generate a dataset with a list of acids.
2. Then create a user written program that willl generate a TSS REP(acid) PASS(*,60) where 60 is the interval of your choosing from the dataset in step 1.
3. Then take the TSS commands generated by the user written program and wrap IKJEFT01 JCL around it and submit it.