Where is miro being configured

Question

Just as migo is configured in mm where is miro configured.
suppose we have a stock of 10 units which includes 4 units whose miro has not been done.
now we have 3 situations:-
1. we have all the 10 units and we want to do miro regarding these 4 units. then the stimulated entry while miro is:-
vendor         10    cr
gr/ir                8   dr
duties a/c        2  dr 
here amount entered in miro is same as po amount.
2. we have all the 10 units and we want to do miro. but now the amount entered while doing miro is lower  than po amount.
vendor    9   cr
gr/ir       10  dr
stock      1  cr
duties      1   dr
3. when we have issued out 7 units out of 10 units and we are left with 3 units. now if we want to have miro of 4 units then the entry will again change
vendor    9  cr
gr/ir       10  dr
stock     .75 cr
price  diff    .25 cr
now i want to know that where in the configuration it has been set up that whenever the invoice amounts differs from po amount then the difference should move to stock and price difference in the ratio of stock left and units for which invoicing
has to be done minus  stock left.
if any one knows please let me know the excat

Answer 1

Originally I had 12 units of this material. I issued 9 units out of these.3 units were left in stock.
6 units were yet left for being doing miro.
But when I try to do the miro for these 4 units I get below written stimulated entry
There is purchase order of 2 line items. IST line item is of (2 units) Rs 2000 and 2nd line item is of (4 units) Rs 8000.
But while doing Miro I have changed the value to 1500 and 7500 respectively.
The result is this entry
1     K     16060071     la-test1 / 122001                                   10,606.74-
2     S     16029001     GR/IR Clearing A/c                                   2,068.65
3     M     23020001     TRASH PLATE FOR MILL NO.6 DIA1067X2100MM          517.16-
4     S     16029001     GR/IR Clearing A/c                                   8,274.61
5     M     23020001     TRASH PLATE FOR MILL NO.6 DIA1067X2100MM          387.87-
6     S     41020061     Purchase Price Variance                              129.29-
7     S     16030011     CENVAT Clearing A/c                              210.00
8     S     16030011     CENVAT Clearing A/c                              4.20
9     S     16030011     CENVAT Clearing A/c                              2.10
10     S     16030011     CENVAT Clearing A/c                              1,050.00
11     S     16030011     CENVAT Clearing A/c                              21.00
12     S     16030011     CENVAT Clearing A/c                              10.50                    
Difference for Ist line item is Rs 500 and for 2nd line item is also Rs 500
But difference in case of IST line item has posted to stock a/c as Rs (500+17.16)
But in case of 2nd line item difference has been divided to stock a/c and price difference a/c as 387.87 and 129.29 resp.
I want to know that why and how it is calculated that what amount has to be posted to stock a/c and what amount has to be posted to price difference a/c.
In obyc we have configured that to which a/c the amount would be posted but where has this been configured that what amount has to be posted to these a/c like in my case the stock a/c and price difference a/c.
Is it linked with tax calculation procedure.
Answer to your question
yes we have assigned GL account for Cost (price) differences for transaction PRD in OBYC(MM-FI integration:--    
we are using ver 6.0 and rest what you asked
SAP_APPL     600     0012     SAPKH60012          Logistics and Accounting