If you still have very old navdata, follow the guide below.
With the latest version (v2.2.0.232), the navdata has now been updated to 2303 (same as simbrief default)
This won't update automatically.
To update, remove the following folder: C:\ProgramData\Fenix\Navdata
Then launch fenix.exe and the navdata will be updated to 2303.
The above only applies for users going from the old default to the new default.
If you want even newer navdata, a navigraph subscription is required: How do I update my Navdata using Navigraph?