I got you, userhelen1.

Setting the payment term will only take a few steps, and you have two options to do it,

First, you can set it up as a default term. Here's how:

1. Click the Gear icon.
2. Select Account and settings.
3. Click Sales on the left pane.
4. Click the edit icon for Sales form content.
5. Select Net 30 for Preferred invoice terms.
6. Click Save, then Done. 

The other option is to set payment terms for particular invoices. This only applies changes to this specific invoice.

That should do it! I'll be right here if you have other questions.