So I'm a complete drone newbie and was flying my spark for the first few times. Everything went fine, but when the Return to Home activated the Spark suddenly gained altitude. Does anyone know why this happened. Is it part of the return to home protocal. Also, i'm generally a quite responsible flier and confident i can fly the Spark home in h 20% battery. Would it be advisable to turn the Return to Home funcation off? Thanks.

You can set Return to Home at Current Altitude to on.. But do you really want to?  The idea is to set RTH higher than anything around where you are flying so that it won't run into anything on the way home.  Also, you should only really use it as a last resort and know  how it works in various scenarios.  You obviously have not read the manual so I would advise you to not use RTH at all.

There are several tutorial videos within this app at the Academy, it's a really good idea to view them all, the manual is also located there in digital format.
Another source for informative video is YouTube, a few of our members have some really good videos for beginners.

I highly recommend you read the manual. RTH is described there very well. Not only are you flying an expensive piece to technology, you are also flying something that can be potentially dangerous to others or property nearby.  Read the manual to know the capabilities of your drone.

Although it may be annoying that the drone rises on a setting that is high, it is much safer to has it this way, rather than having the hazard of the drone crashing into objects on its way back home. Return To Home is a great feature because the drone will always have enough battery power to safely land.

it is not advicable to turn RTH off. Also in mid air you can turn RTH OFF by shifting the normal mode switch to SPORTS mode.
If you disable current RTH altitude settings in the menu, you will not see the SPARK incrementing in its altitude during RTH.

It is recommended that you enable  beginner's mode in the settings during your initial flights with SPARK to avoid any mishap.

RTH is a common cause of issues. BUT that is usually because the pilot does not understand it / expect it.
There are various options. All suit specific situations.
As suggested, I would try and find some tutorials and see which setting suits you.

Unfortunately you can't turn off "SMART RTH" for the spark
The best you can do is press "CANCEL" when the 10 seconds countdown starts

I keep posting this video from Kloo Gee. Its the best explanation of Return to home I have found.