In QuickBooks Online (QBO), there's no option to directly add social media buttons to outgoing invoices, Johan10. However, I'll provide a workaround to achieve this.
To start, you can personalize and effectively use the email body and footer to add your social media based on your preferences.
Here's how:
- Log in to your QuickBooks Online account.
- Go to the + New and click Invoice.
- Scroll down and enter your social media information in the Message on Invoice based on your preferences.

I'll provide a screenshot for preferences:

Additionally, I will provide these links that discuss how to modify your templates to improve their look and introduce you to the process of setting up and using progress invoicing to simplify your billing procedures and better manage your cash flow:
The Community Team is always on standby to help with any additional questions you may have about personalizing invoices or other aspects of the program. Feel free to use the comment below for any inquiries.