Set Attitude Estimation Algorithm
To use all the navigation features using GPS,select the GPS navigation (INS13) attitude estimation algorithm
Go into Attitude page > Settings > Attitude Estimation Algorithm, select GPS Navigation INS13, and Save.
Set the flight mode
Go into Input page > Flight Mode Switch Settings and affect PositionHold to one flight mode position.
When engaged, PositionHold hold current vehicle position using GPS sensor and without stick interaction.
Altitude can be maintained if one VtolPathFollower parameter is set:
Go into UAVOBrowser and find Settings > VtolPathFollower > Thust set to Auto
Save settings with 
button.