Thank you, that makes the question clear - so to the response:
This is basically up to the configuration and user rights set in the operator record. I have checked some operator records and security profiles, and I can confirm that the Request.Approver user by default cannot open a new Change - so if you need approvers not to be able to open changes themselves and then approve them, just check Change.Approver operator record - in general, if an operator has change approver user and security role, he should be able to approve changes and not be able to open new ones.
You could test also with OOB Change.Approver - when login with this operator, and you will see that he has no access to Change Management > Change queue.
we had the same requirement, and we accomplished it by adding a condition to the change phase approval control. for instance, we have a single phase in which all approvals take place, so the condition for the approval control in that phase is:
operator()~=orig.operator in $L.file and operator()~=requested.by in $L.file