Re: Android 5 and LG3 Problem
The above are correct, it's the new way of showing recent applications.
Currently, you can change this only with rooting your phone, something you may not want to dive into.
Alternatively, if you wish to go back to KitKat firmware you can flash it back to a stock firmware using known safe methods. If you want to know about either of these solution, just let us know here in this thread.