1. When you are signing a workflow, you can add one or more approvers with authorization and the workflow will follow the new delivery order after you agree the workflow. 

2. Open an incoming workflow in the Inbox.   In "Delivery order" field, click "+",  a blank record will be added for choosing a new approver  with "Review decision" check on the right hand side.

3. Click "Agree" and "Done" to let the workflow move to the next person by following the new delivery order.