If you install from an approved source (Google Playstore etc.), it will auto-update unless you turn off auto-updating.
If you download from Kodi, it will not auto update, but will inform you of newer releases.

If you want an old version of Kodi, you can get it here;
Code:
http://mirrors.kodi.tv/releases/
Most Android STB's would use 32 bit v7arm.