How to remove 650 NAV from Nav source?

[Pilotkms]

HDX and 650. Initial plan was to do an ILS. Entered NAV frequency in 650. Selected NAV as source in HDX. Decided to do an RNAV. Couldn’t get the source on HDX to change from NAV. Usually indicates 650 for RNAV. Stayed NAV no matter what I tried pushing. Gotta be something simple. Secret button??

 

[Danerazz]

Do you have the GTN set up for Auto VLOC/GPS switching?

Make sure the GTN said GPS on the bottom of the screen.