Is there a way to change the price level when entering a sales order that will apply to every line item, as opposed to changing it at the line item level?

customer specific price level (Customer --> Financial subtab) is most likely what you want.

So the specific situation is that we want to be able to apply a discount to an order but have it discount at the line item level. So this price level wouldn’t be unique to the customer but could be used across any customer when we want to use that discount

I wish this was a feature too. We have a need to set the price level on the header of the transaction and have it apply to all lines. A script is the only way I’ve found to do this Our customers don’t always use the same price level it more depends on the order type for us