CJ is responsible for each order from CJ.
For Fresh CJ, you can open a dispute in Orders > Orders Fulfillment > Pending/Processing/Dispatched/Completed. Check the specific tutorial here: New CJ: How to Open/Close a Dispute on CJ?
For Classic CJ, you can open a dispute in Orders > Orders Fulfillment > Processing/Processed/Completed > Operation > Dispute.
Also, for bulk purchase orders starting with "ZF", just click the "Dispute" button to do it.
If you want to close/cancel the dispute, please go to AS service center > Awaiting response > Dispute reviewing > click "Close" at the bottom of the page.