Change authority

Answer:
If we stick to ITIL or ISO 20000 - there is no Change control board. ITIL defines only Change Advisory Board as an authority to authorize changes. But, you will need to define what kind and what levels of changes you have and who authorizes them.

Here are the articles that can help you:
Change Advisory Board in ITIL – advise, approve or what? https://advisera.com/20000academy/knowledgebase/change-advisory-board-itil-advise-approve/
ITIL V3 Change Management – at the heart of Service Management https://advisera.com/20000academy/knowledgebase/itil-v3-change-management-at-the-heart-of-service-management/

Also, our free webinar can help you as well: An overview of the ITIL Change Management Process https://advisera.com/20000academy/webinar/an-overview-of-the-itil-change-management-process-free-webinar/