Where can I modify these values so that I can use them on my Garmin
In the Garmin Connect app on your smart phone, I think 
Sorry, I don’t see it …
In the Garmin Connect app, go to Devices, then to your Edge (needs to be connected), Activities & App Management, Data Fields…
You can also use the Connect IQ app, chose your device in the top right corner (again, it needs to be on/connected), then go to My Data Fields, chose the field you want to modify and got to Settings…