Welcome.
You can halt the climb to RTH height by
"If the aircraft is at an altitude of 65 ft (20 m) or higher and has not yet reached the RTH altitude, the
throttle stick can be moved to stop the aircraft from ascending and the aircraft will fly to the Home
Point at its current altitude (only available with firmware v1.0.0.0. This function is not available when
the firmware is updated to v1.1.0.0 or later)"
The above is from page 15 of the manual.
I would suggest that RTH height is something that should be set each time you fly in any giving/new location. Minimum heights need to be adjusted to avoid obstacles, trees, building etc. and I aim to clear an obstacle by around 30ft/10m. Setting a unnecessatily high, cover-all-situations RTH height wastes battery power in both the ascent and descent phases of the process.
It may also put the drone up into fast wind, wind speed tends to increase with height above the ground (AGL) and wind can be a problem.
Note you can reset the RTH height whilst the drone is in flight but you CAN NOT reset the RTH height whilst the drone is climbing to RTH height. I have forgotten whether or not you can change the RTH height whilst the drone is actually flying towards home but if you try that and aim to reduce the height be careful, ensure there is nothing too close beneath the drone, the drone might possibly descend. That may be unlikely but it could be an expensive way of determining one way or the other.
I would also suggest you read up on the various distance thresholds related to RTH behaviour, the behaviours change with distance and can catch you out.
With regards to "It landed very elegantly but nowhere near the take-off position". Providing the drone has sufficient satellites to establish, to its satidfaction, that it knows where it is the drone normally resets the home point as it takes off, and fast flashes the rear LED, I watch for this. If the drone takes off with insufficient satellites and is flown away from the take off point then it will set the home point to wherever it is when it finally gets sufficient satellites. I often have to take off with insufficent satellites, I may well fly it away from the take off point and or make it climb, to the limited "no GPS" ceiling, but once it has established a home point - somewhere, I bring it back over head and reset the home point to the drone's postion i.e. where I am.
