Yes, QuickBooks keeps your data organized. The system only depends on how the transactions are being recorded. With that, transactions should associate with the correct customer you used. Also, it should normally not be messed up with other details you've entered in QuickBooks.
In this case, we can perform some basic troubleshooting steps to get this done. If you haven't tried it, please follow the information below.
Step 1: Use an incognito window:
For Google Chrome browser: Ctrl + Shift + N
For Mozilla Firefox browser: Ctrl + Shift + P
For Safari browser: Command + Shift + N
This prevents your browser from storing additional cache files that could be the reason why the transactions and customer information are not organized.
Step 2: Delete cache and temporary internet files: