Hi KerryG_25,
Thank you for checking the help articles that were sent by Shella and Doreen.
You may edit and remove the shipping address by deleting it or leaving it as blank when you create a purchase order.
As for the purchase order number as of now we don't have an option to remove it as it is system generated and the PO number is important for managing and tracking purchases.
Also, you may edit your business under under Business settings you may find if you will check this help article http://help.myob.com/wiki/x/165qAg.
Lastly, changing or editing font are also not available in MYOB Business or in the browser version.
Let me know if you still need further assistance.
Cheers,
Jem