The Application that is being used with the NGT-1 is responsible for configuring the NGT-1 for each session when it opens up the COM port to the NGT-1. The end user should not need to configure anything, and any manual configuration could be a waste of time.
If you manually change the “Tx PGN Enable List” inside your NGT-1 (using NMEA Reader) those changes may well be overwritten when you start up your software and it configures the NGT-1 to what it knows it needs. Furthermore, you can enable PGNs in the NGT-1’s Tx PGN Enable List as much as you wish but if the software you are using isn’t actually sending those PGNs (to the NGT-1) nothing will appear on the network. If software has been designed to transmit a PGN it should set up the NGT-1’s “Tx PGN Enable List” accordingly to allow those PGNs to be transmitted on the NMEA 2000 network.