Why when I've uploaded a receipt, can't I "add a line" to that receipt?

Your continued engagement in the Community space is appreciated, jay87. I'd be pleased to assist with uploading your sales receipts within the program. 

Sometimes QuickBooks Online (QBO) may behave unusually due to stored internet cache files. Let's carry out some basic troubleshooting steps to resolve the issue. To begin, use an incognito window or a private browser and try the activity again. The keyboard shortcuts are as follows:

• Safari: Command + Shift + N
• Google Chrome: CTRL + Shift + N
• Mozilla Firefox or Microsoft Edge: CTRL + Sh

If it works, go back to your usual browser and clear its history to start anew. If not, I recommend using a different supported browser, as the QuickBooks version you're currently using may have a temporary malfunction.

You're welcome to use these articles as a reference for managing receipts in the future:

•  Email receipts and bills to QuickBooks Online
• Customize invoices, estimates, and sales receipts in QuickBooks Online 

Kindly leave a comment below if you have further inquiries. Our committed team is ready to offer the assistance you require to guarantee a smooth sales tracking experience. Take care.