I feel silly even asking for advice on this (paypal)

[klash-anole.livejournal.com]

I've been doing invoices for taking paypal commissions. I love the organization and not having to worry about customers putting incriminating subject lines or doing mistakes like sending money as a gift, etc. The problem is... I cannot figure out hot to turn off the shipping option. I'm afraid this is going to become a problem in the future, since I work exclusively with digital art. Am I overlooking something obvious? If it can't be turned off, is this going to get me into trouble some day?