Default Location For Cache Files Refuse To Change!

In the Project Settings I tried many times changing the location of the Cache files and saving the changes as the default. But as soon as I close the project and reopen it, the Cache files location reset to as before!
Here is the new location:

And I saved the settings as the default:

But if I close the project and re-open it, the Cache files location return to the old default:

BTW, this do not happen if I change Project media location and Proxy generation location .. only happens when changing Cache files location.
Any idea what is going on?
Here is the new location:

And I saved the settings as the default:

But if I close the project and re-open it, the Cache files location return to the old default:

BTW, this do not happen if I change Project media location and Proxy generation location .. only happens when changing Cache files location.
Any idea what is going on?