Have paid a supplier for goods but need to return some & will receive money back into bank. how to enter in QB as transactions will be shown separately on bank statement

If you purchased inventory, then you need to do a supplier credit and select those items/qty returned

when you get the deposit, choose accounts payable as the source account for the deposit, then use pay bills, select the bill the deposit created and apply the supplier credit

If you are returning goods that were not inventory, then just use that same expense account (as you used for the purchase) as the source account for the deposit