Investment orders settlement as Summary and Line item settlement

HI, I am having an issue with Investment order settlement.

Earlier the Order settlement was made with Summary settlement, later on we decided to do it on Line item settlement where we can select particular Invoices (Line items) to do the settlement to the fixed asset.

The movement we changed the settings from summary to the line item settlement, the old settlement rules and the old balances which are already capitalized are getting affected.

Do not know what could be the reason, can any one suggest?