sales ledger control a/c

Hallo,

May I ask in which cases we’ll have a credit balance to a sales ledger control a/c under the title Owing to customers (which is not the same as return inwards), I thought owing to customers belongs to A/P and I excluded it at first, but then I saw they credited the sales ledger control a/c with it?

From the following information, draw up a sales ledger control account for the month
of February 20X7 by entering the missing figures in the control account below:
……
Owing by customers at 1 February 20X7 103,670 – Debit
Owing to customers at 1 February 20X7 1,400 – Credit

Thank you!