It's possible that you have turned on the Pre-fill forms with previously entered content function. Thus, the program automatically fills the details based on the last bill for the same supplier.
Here's how we can turn off the said function:
The details of the last bill won't appear again when you create a new one for the same supplier.
If the same thing happens, we can do a few browser troubleshooting steps. Cache files can speed up browser processes, but they can also cause unexpected issues. Here's how to get rid of any cache-related issues:
Let me know how this goes so I can help help you more if necessary.