Mandatory DEFAULT for Billable and markup percentage

Mandatory DEFAULT for Billable and markup percentage

Hello.  So we have been using books and process bills from vendors that are to be invoiced to customers.  When we convert from a PO to a bill we can enter the customer name on the line items and that is great.  However, we would like to know if the default for that process can ALWAYS be billable no matter what.  ALSO, have it a mandatory markup as well. 

I know there is a markup percentage in settings but it is inconsistent as to when it shows up.  We have had many situations where we process a bill and enter the customer information but it does NOT show up as billable so we never bill the customer for that item.  We need to manually audit this process.  Also, when billable is selected many times it will default to zero instead of the default markup %.  So we need to audit this as well.

So is there any way to make the items billable and a default markup MANDATORY all the time? 

Perhaps I am missing something in the settings. 
Thanks for any help