Inconvenient "read-only" finder mode
The properties for any Finder window are stored in the .DS_Store file located at the root of the directory. It should have nothing to do with the permissions of the file, unless the active user account is not a member of the wheel group (very unlikely).

You should be able to change the view configuration of the Macintosh HD window and have those settings stick. If not, there is the chance that the .DS_Store file has become corrupt somehow; deleting the file and letting it rebuild should solve the problem. In Terminal:

sudo rm /.DS_Store

Re-open the window and set the view to your liking.