[Koha] Serials framework

[Paul]

Apologies if the answer is available, I just can't find it.

Serials framework, Leader 000 position 7, must be changed from m - 
Monograph/Item to s - Serial.

How do I make "s" the default in that specific framework (obviously without 
modifying default, books etc frameworks), or do our cataloguers have to 
remember to change it?  Even after setting 942$c to serials, the "m" keeps 
appearing in the leader.

Thanks - Paul