Is there a way to automatically update the purchase cost of stock items, when I raise a PO or Bill?

a PO is non posting, it is just a memo of what you ordered

but the bill does record the purchase (qty and cost)

QBO uses FIFO so the first purchase date and cost is used when you sell, until that qty for that purchase date is gone, then the next purchase date is used

as a result the cost price on the item screen is not real accurate, nor  is the average cost shown in the inventory valuation report

Why can't you make the bill pull the new price off a bill?  I used to use sage and they had this facility, this is definitely lacking in QB and is is time consuming and tedious having to two jobs when it could all be done in one go.  Surely this is something which could be done? Also the problem with not being to automatically set a customer or supplier discount so it isn't missed, or to be able to put a customer account on hold if non payment occurs, these are all things lacing in QB which are there with sage and other products like xero. When will these things be implemented into QB to make our process easier?

Hi, Hgill1.

Allow me to provide some updates regarding product-related in QuickBooks Online.

At this time, there isn’t a specific time frame as to when this feature be available. Our development team is constantly working to improve the product and appreciates the help of users in bringing things like this to their attention. 
 

In the meantime, I'd encourage you to visit our QuickBooks Blog site for product updates as well as business tips from our accountant.

Also, you can always visit our Help Articles page for QuickBooks Online in case you need some reference for your future tasks.

Drop me a comment below if you need further assistance with QuickBooks. I'll be more than willing to lend you a hand. You have a wonderful day!