Tim:
I think if you want to modify *anything* in the zone files, you'll first need to stop the service then delete their journal files, before editing them.
Chris Adams:
Or just freeze/thaw them - no need to stop the server, and you should never delete the journal files.
I can't remember where I found out I had to delete the journals to get changes to the zone files accepted, it's just too many years ago. But if the journals were present, the moment the server started, it re-read the journals to rewrite the zone files.
In the stopped state, the zone files are in their most updated state, and the journal files are not needed. So you shouldn't need to keep them, and I've never been able to detect any adverse effects from deleting them. But keeping them presents the problem I just outlined.
I'm talking about hand-editing the zone file, here. If you were changing records through some interface belonging to BIND, like rndc, that's a different matter. It will be doing it for you, or should be.