The u-blox GPS is told to remember its settings

What ArduPilot says:

• GPS N: u-blox saving config

The u-blox receiver has accepted all of ArduPilot's settings, and ArduPilot now tells it to store them in its own memory, so that next time it starts already configured. GPS_SAVE_CFG decides: 1 always saves, 2 (the default) saves only when something had to be changed, 0 never. It is done only while disarmed, and tried at most 5 times, 5 s apart.

If the line returns at every start, the receiver is not keeping what it saves: many small modules have no flash and rely on a backup battery or capacitor that may be flat. It costs a few seconds at start-up and nothing else.

Parameters to look at