Sales order approval

Hi was wondering if someone can help.

we currently have a workflow which will put a sales order in to pending approval status when a customer is over the credit limit. which is fine however in order to release these orders we have to go into each one and due to our business we can have a high number of sales orders and this can take a couple of man hours to complete this task.

There is a native approve sales order screen linked to a reminder that you can batch approve SO's which would speed this process up.

I have been looking at how to renable the native credit hold process. I am not sure what I am missing but when I enable this I can set the preference to warn orders or hold however with warn the SO is saved but goes straight to pending fulfilment not pending approval and hold prevents the order being save.