Hello, @M00S389.

Let me share some information about the large white space on the Purchase Order window.

The large white space that you see on the right side of the Purchase Order window is a summary of the information of your vendor. 

You’ll notice it when you put the name on the vendor field. It will also show all of the recent transactions that you had with your vendor.

To remove this, you need to click the arrow button at the top of this window pop up. 

Please see the screenshot below. 

To avoid errors or unexpected behaviors while using QuickBook Desktop, you can update your QuickBooks to its latest release: Update QuickBooks Desktop.

Please let me know if you have any other questions. I am here to help. Have a nice day!