Hi KrisMc,

Since we've done all the basic trouble shooting steps above and still unable to access customisation with sales forms. I would recommend contacting our Customer Care Team. That way, they can check the QuickBooks file and they can ask for your details in a secure form.

1. Sign in to your QuickBooks Online company.
2. Select Help (?).
3. In QB Assistant, enter the topic you need help with. You can also enter questions.
4. Select Contact Us to connect with a live support agent.
5. Choose a way to connect with us:
 

• Start a chat with a support expert. Live chat M-F, 8:30 AM to 6:30 PM and S-S, 8:00 AM to 8:00 PM, AET.
• Call us. M-F, 8:30 AM to 6:30 PM, AET.

Leave a comment below if you need more help with QuickBooks Online. I'll be here to help. Have a nice day!