Change the Default Approver
Go to Portfolio > Portfolio Summary
Double click on the Asset (Company)
This will take you to the Investment Status > Overview tab.
Click on the Investment Director card:
In the pop up window, use the drop down to select a person to be the Investment Director (the default person responsible for approving KPIs).
You can also select / update a second user as a Deputy who will also be able to approve results.
Click OK.
Change an Approver for a single Objective
If you need to select a different approver from the default to approve a specific Objective:
Go to Portfolio > Portfolio Summary
Double click on the Asset (Company)
Click on the KPIs tab
Click on the Approval Settings button.
In the Approval Settings window you can use the drop down on the right hand side in the Approver column to select a different person to be the approver. 
As soon as a change is made to the approver, any pending approvals are switched to the new approver, straightaway.
The summary emails continue to be sent out to approvers once a week, on Mondays.
Reminder emails for outstanding Approvals can be sent from Portfolio > Admin > Companies tab.