Presently you can't. it will rise to 10 meters, if below, and return home. If above 10 meters, it will maintain current alt and return home. It has been requested numerous times as an upgrade and i'm sure will soon be implemented.
This has been mentioned many times, unfortunately as others have stated it cannot.. Yuneec knows about this request I have emailed them so have others even spoke to CS about it. I'm sure they read this forum so hopefully they will fix it in an firmware update. Hint, hint, Yuneec.