You can't change this number in easy way if this be so easy than all who convert from 37xx to 34xx will change this number.
Garmindevice.xml is created automaticly on boot so if you change anything inside xml after new boot will be overwriten.
PLEASE read first post and tutorial Index and you learn a lot of thing and you will also figure out that you can't change number on first screen if you change something in xml.
Only way to change this number is in reg 41 but you can brick your device and this is reason why nobody change this number and you also must know how to convert reg41 that you can then see what is inside this region.
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