Initial channel settings (pan / volume), but also default speed and tempo are typically handled individually per sub-song in some of the formats we support (e.g. PSM, MED). Currently OpenMPT either converts these to pattern commands (PSM) or just imports one set of global defaults (MED).

These global settings should really be handled individually per sub-song, not only for the sake of better PSM / MED support but because it's a sensible thing to do in most cases. However, there are also situations where this might make editing more cumbersome, for example if all subsongs are supposed to have the same channel names and volumes - with the new implementation, one would have to update these manually for each sub-song. Also, the channel re-arrange feature is not aware of sub-songs, which may also lead to confusion (all patterns will be touched).