Hi there faisal-ali-srjca,
Thanks for reaching out about your account balances. QuickBooks Online is a great tool able to help you create and send invoices to your customers so they know the amount owed to your business. I can point you in the right direction for assistance with this.
To see which customer has a balance open, I recommend going to the Sales tab, then customers. In this section, you'll be able to see the open balance of every customer, so you can see which one supplier has an open balance that shouldn't, or that their balance is incorrect.
For further assistance with these transactions with multicurrency that have a slight imbalance, I recommend speaking to your accountant. Their expertise will be able to assist with analyzing these transactions with you to be able to locate the difference in foreign currency. You can invite your accountant to your books by going to the My Accountant tab and entering their details. You can also find an accounting professional near you that has experience using QuickBooks programs by clicking on the Find a Pro to Help option located in that section.
If you have any other questions, feel free to reach out here.