If you require to re-order subflows in a control flow (series, parallel or condition flow), the following will assist:
Illustrated in the image below is an example of a series control flow with 3 subflows.
To re-order the subflows, click on the highlighted icon on the control flow as per the image below.
The below page will appear. It shows the subflow number with the subflow ID.
To re-order the subflows, left-click and hold the subflow and move it above or below the other subflows. You will see the subflow ID changing to the new subflow order number. Then click on the Save Control Step button. Your webpage will refresh with the new order as per the below image.