Settings > Product Settings > Require Review and Approval on Procedure Publishing
  
Require Review and Approval on Procedure Publishing
The Require Review and Approval on Procedure Publishing setting allows organization administrators to require a minimum number of users that must review and approve a procedure before the procedure can be published. This setting applies to all procedures in an organization.
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The required number of approvers are only enforced on newly submitted release candidates. The required number of approvers will not be applied to any pending release candidates.
For more information on review and approval, see Approval Workflows.