I am using a CSI DGPS device, but the GGA output is more precise (more digits) then the GLL, how can i force the software to use the GGA sentences only ?

In Hydromagic, it is possible to specify which NMEA0183 sentences should be encoded.

To do so, select the NMEA0183 channel the GPS device is connected to, and click the "Select Sentences..." button.

The "Select Sentences" dialog should now appear. It allows you to select which sentences to decode by (de)selecting them in this window.

More information on configuring NMEA0183 channels can be found in the manual:

Configuring an NMEA0183 compatible GPS