I make a change and then I git stash and then I git stash apply
My question is
why after I git stash apply
If you find that your changes are unexpectedly staged, do:
git reset HEAD
I usually only see this if there is a conflict when applying the stashed changes. You will want to check to see whether this is the case before doing the git reset.
The git stash command is the most appropriate command for your use case. I use it all the time for exactly this purpose.