Thanks for clarifying that, Tina. The Notes section in the customer information field can contain up to 4000 characters.

For more information about file size and feature limits in QuickBooks Online, check out this Community article: https://quickbooks.intuit.com/community/Help-Articles/QuickBooks-Online-file-size-and-feature-limits....

I hope this helps. Let me know if you have any other questions. 

Have a great day!