The FTM-400 had two settings for the compass to control the setting of Heading Up or North Up.  One is in the Display options (Settings | Radio Menu Settings | Common 1 | Display | Compass.  The other is in the Settings file under APRS | APRS Compass. 

The FTM-300 has the option for the compass in Display but does not have a similar option for APRS compass... or at least not one you can find from the face of the radio.  Turns out, the option is there and it does exactly what you would expect.  It sets the compass in APRS mode to Heading Up or North Up and the compass responds to that change from the programmer. 

So, we left it in the programmer. This is one of those extras that you can't change from the face of the radio but you can set from the program. 

May 18, 2021 - Always believe you can.