Refurbish Order Settlement Account

[sapnisme]

Hi All,
I've made refurbisment order is complete up to Settle.
Its cost details as below :
65810001 ABCD 200
65330001 EFGH 150
90000008 INT_LAB 50
Debit : 400
67880051 OFFSET REFURBISHMENT 400-
Settlement : 400-

My Question is :
1. Why Settlement Account is 67880051 OFFSET REFURBISHMENT?
2. How to change its settlement account to be debet accounts (65810001 and 65330001) ?
3. Where its Config?

Thanks

[sapnisme]

Please help me..