hi,
For this you can use playerprefs actions.
playerprefs is perfect for this, but not for saving scores/coins/etc... as it is very easy to hack.
It is ideal for preferences
so at the start of your game you need to use a 'has key' 1st to see if the key reference exists.
if not you can do a 'default' save.
then if it does exists the you can get the value with a playerprefs get action and if you change the value you need to use playerprefs set actions.
to reset (delete all saved data) you can use playerprefs Delete All