@Yoyo000 

RE: I want to add 2000 items in one invoice with its quantity. Is there a way to copy and paste the items from excel to one invoice?

Unfortunately no, there isn't a way to paste such items.  You can however import the entire invoice. If this is something you'll need to do over and over, you might want to use an app like our BRC IIF Transaction Creator Pro  to import your data instead of manually entering it.