Change Management Workflow at PO Level

I have a PR that gets converted to PO. Requirement is to approve PO then if any changes to be managed by 'Request Change' at the PO level. I have already got PO workflow setup and works fine.

However, when I activate 'Change Management' from the Procurement and Sourcing parameter. PO gets approved automatically bypassing the approval stage. I would like to have PO at open and draft state for user to manually review and approve > then PO confirmation. For whatever reason if a PO change is needed user should then be able to use 'Request Change' tab. 

Is there any added setup for Change Management to stop PO approval beforehand? Please advise.