It isn't the experience we want you to have, architect. I'm here to help you successfully add a website to your customized sales form in QuickBooks Online (QBO). Let me provide more details below.
To ensure that your website URL is accepted when you input it into the customized sales forms in QuickBooks Online, it's important to include the complete address of your website. This includes the protocol (e.g., http:// or https://) and any subdomain (e.g., www) your websites use. Including these elements ensures the form's validation process recognizes and accepts the URL.
I'll attach an image for reference:

Regarding your difficulty in attaching a photo, could you please provide more details about what exactly occurs during the process? Did you encounter any error messages, or does the option to upload not appear at all? Understanding these specifics will help us better address the issue and ensure we provide you with the most effective assistance.
You can also explore these resources to help manage your customer balances and provide concise summaries of all transactions:
If you encounter any additional challenges or have more questions about adding websites when customizing sales forms in QBO, please don't hesitate to post them here. We'll be sure to answer them promptly!