Though change is a significant part of today's work environment, it is often difficult and problematic for employees as well. My question is; Can new...

Though change is a significant part of today's work environment, it is often difficult and problematic for employees as well. My question is;

1. Can new employees change a company's culture? If so, how?
2. Are there conditions under which change is not possible? If so, what would such conditions be?
3. How can leaders take steps to enrich and more effectively leverage their culture to affect organizational change?