Is there a way to set up a favorite customer so that they always receive a 10% discount on everything they purchase?

Hello cgostick-telus-n,

Welcome back to the Community. I trust that business is going well on your end. I can see the benefit of being able to set up a discount for your favourite customer and I'll be happy to share more info. 

At this time, there isn't a way to set up an automatic discount for your customer. I recommend sending this as feedback to our product developers so they can look into including this feature in future QuickBooks updates. You can send feedback by clicking the Gear icon and looking for Feedback. 

The good thing is you can still manage your discounts manually in QuickBooks. Here's to turn on the discount feature: 

1. Click  Settings ⚙ > Account and Settings.
2. Select the Sales tab.
3. In the Sales form content section, click on the pencil ✏ icon.
4. Turn on the Discount setting
5. Hit Save and then Done.

For more info on how to apply the discount on invoices, check out this article: Add a discount to an invoice or sales receipt in QuickBooks Online. Another workaround would be searching for third-party apps that'll help you automatically apply a default discount of 10% for your customer. You can search for these apps on our app store by visiting www.apps.com. I suggest choosing an app that suits your business needs based on the app description and reviews. 

In the meantime, feel free to ask other questions in the comments below. I'll be here to help.