The location of the serial number varies by the design of the headphones:
The serial number will be listed alongside other device details like the firmware version. Using the Serial Number for Authenticity and Warranty Where is the serial number? - JBL Support
Depending on your specific model, the serial number can be found on the physical hardware, the original packaging, or within the official mobile app. Where to Find the Serial Number on the Hardware
: The serial number is consistently printed on the bottom or back of the original box , often near the barcode.
The Essential Fingerprint: Understanding Your JBL Serial Number