Windows 7: Problem with file/folder permissions

So recently I reinstalled windows, however I always get this problems and it bugs me.

Basically I lay my computer out like this all user data is saved on the an external hard drive, that's how it was like when I had my other OS. Now folders are given permisisons so users can't access other users data, however when I re-installed windows now it tells that I don't have access to these folders becaause of permissions.

Yes for some reason I think the hard drive remembers those permissions and so on, check my attachment i got a dozen folders here whats the easiet way to remove the permissions and apply to different users?

I apply to one folder and sub folders and files but still some folders in a folder will have restrictions.

Guys what's the easiet way to get rid of this?