Comments
The comments field is only for comments about this individual reservation/stay.
Those comments will not be visible by the client whether it is on the Confirmation, the Reg Card, or the Folio.

If you are a Best Western Hotel connected to the 2way, those comments will be synced as part of the reservation with Member Web.
HSK (Housekeeping) Instruction
Those comments are internal and also not visible to the client.
They will be shown on the Room Assignments sheet for the housekeeper who will have the room number on her/his sheet.
Internal Comments
Those comments come from the Guest Profile.
The feed of this section only goes from the guest profile to the reservation, not the other way around.
If you want to modify the comments and save them for a future reservation, you have to do it from the guest profile directly in Sales & Marketing > Guest Profiler > Guest Profiler.
The Guest Profile Comment field will accept up to 100 characters.