Discounts on invoices: I offer discount to some customers but there doesn't seem to be any way of offering that when I write an invoice?

Discount is an option that needs to be turned on in QBO, info217.

You can go to your company settings to enable this feature. When it's on, you'll be able to add a discount on a customer's invoice. 

To get started, you can follow these steps:

1. Click the Gear icon in the upper right-hand corner of the Dashboard.
2. Under Your Company, click Account and Settings.
3. Go to the Sales tab on the left panel.
4. Click the Sales form content section to open it.
5. Check the tick box for Discount.
6. Click Save, and then Done.

Then, go create an invoice for your customers and select whether to apply a discount percent or value. You'll see these options in the lower-left hand side of the invoice right below the Subtotal.

These steps will surely help you and other customers out. Please keep me posted if you need anything else. Thanks.