On the CRTJRN comand there is a parameter named MNGRCV which is set to either *USER or *SYSTEM to say whether you or the system does management of journal receivers. You can still do a manual CHGJRN and it will do a *CONT on the sequence numbers if your command default is set to this. However, if you look at the help text on this parameter in the CRTJRN command it states that at IPL time a *SYSTEM controlled journal will have a CHGJRN done to it and the sequence numbers will be reset as long as commitment control is not in place.
If you don’t want this to happen then both of your journals should be set to *USER for journal management. The CHGJRN command will let you change this parameter on the journal.