TYPO3 v7 has reached its end-of-life November 30th, 2018 and is not maintained by the community anymore. Looking for a stable version? Use the version switch on the top left.
There is no further ELTS support. It is recommended that you upgrade your project and use a supported version of TYPO3.
The Page TSconfig primarily concerns configuration of the modules in the TYPO3 backend. It may also relate to values in the frontend display occasionally.
The Page TSconfig for a page is accumulated from the root and extends to cover the whole branch of subpages as well (unless values are overridden further out).