If anyone else want to know more about this, here is a good article that breaks it down and details the risks:

http://bitzuma.com/posts/five-ways-to-lose-money-with-bitcoin-change-addresses/

Hi,

Thanks for putting together the video.

When I tried sending a test transaction of 1 OK to Bittrex from my ROKOS wallet, unfortunately the transaction also sent 363.1799 to another address, I believe this might be a 'change address'.

My ROKOS OKCash wallet shows that I have sent 1 OK with the balance adjusted for -1 OK, but the OKCash Explorer at https://chainz.cryptoid.info/ok shows my balance adjusted for -364.1799.

Please could you help me:

Understand what has happened and why?
How to get my OK back from the change address
How to prevent this happening again.

Many thanks in advance,

Tumble23

P.S. Generous donation for timely, high quality support offered.