Linux answers...
To answer the question explicitly:
To only change user owner of this folder and everything within it owned by a specific user:
sudo chown --from=ownerOld -Rc ownerNew /this_is_my_path/
A few variations to help understanding of syntax which help protect you from catastrophe:
To only change user owner of everything within a folder (not the folder itself) owned by a specific user:
sudo chown --from=ownerOld -Rc ownerNew /this_is_my_path/*
To only change user owner of this folder and everything within it owned by a specific user & group:
sudo chown --from=ownerOld:groupOld -Rc ownerNew /this_is_my_path/
To change user & group owners of everything within a folder (not the folder itself) owned by a specific user:
sudo chown --from=ownerOld -Rc ownerNew:groupNew /this_is_my_path/*
To only change group owners of this folder and everything within it owned by a specific group:
sudo chown --from=:groupOld -Rc :groupNew /this_is_my_path/
To only change group owners of everything within a folder (not the folder itself) owned by a specific user & group:
sudo chown --from=ownerOld:groupOld -Rc :groupNew /this_is_my_path/*
do not use the ":" or place the group name if you do not wish the group to change.
also you will need to be the owner and have write access so sudo is probably required.
Remember this is a dangerous command DO NOT run on root "/"
If you get it wrong you are in a world of hurt.
Triple check it before you execute it.
switch c is to show changes.
switch R is recursive
/path/* will not pick up hidden files.