Thanks for becoming part of the Community, kiml3.

You can set customized late fees for individual customers from their profiles.

Here's how:

1. In your left navigation bar, go to Sales or Invoicing.
2. Choose Customers.
3. Pick the customer you'd like to customize.
4. Click Late Fees.
5. Decide how you want to customize. You can either choose Waive late fees, which prevents them from being calculated and applied to an overdue invoice for the customer; or to Override the default late fee settings, which creates a new set of rules that only apply to the customer being worked with.

If your late fees are being overrided, it's possible you've turned on Waive late fees, which will prevent them from being calculated for the particular customer. You can use the steps above to check if it's turned on, and turn it off if necessary.

I've also included a detailed resource about working with automated late fees which may come in handy moving forward: Set up & apply automatic late fees to invoices

Please feel welcome to send a reply if there's any additional questions. Have a great day!