update

HI everyone.
I have a tv box/android 5.1.
It comes a kodi v16.
I want update to a 17 but don´t know how.
At playstore I can´t because the last version there is 16…
At website there are several versions but I downloades all then and it stop saying “can´t finish install”
Someone help me?
( sorry about my bad english)
thx