When I checked Profit and Loss by Customer, I found that my supplier is included in the report. Even though I didn't add that supplier to the customer list

Hello, aini-asiacommerc.

I've checked your post and found that you've posted twice about the supplier shown when running the Profit and Loss by Customer report. The duplicate one was already answered by my colleague MariaSoledadG.

You can view her answer by visiting this link: https://quickbooks.intuit.com/learn-support/en-sg/reports/when-i-checked-profit-and-loss-by-customer-i-found-that-my/01/1066342#M139.

I'm also adding this article about personalizing reports to show only the information needed for future reference: Customise reports in QuickBooks Online.

You're always welcome to post your reply if you need further assistance with reports. We're here to help you.