You use why with 'not' in questions in order to express your annoyance or anger.
Definition of why adverb in Oxford Advanced American Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more.
To optimize multi-user and guest devices, Windows provides options through a feature called Shared PC. These settings are designed to improve the experience for all users on the device, and to reduce the administrative overhead caused by the maintenance of multiple user profiles. This article describes the different options available in Shared PC.