This is a form which can be opened from the Accounting Tables switchboard.

In this form, you can "Find" the asset you want to work with, and display the Opening Balance data for all of the Funds and Liabilities belonging to that asset. As you enter or modify the opening balances of the funds/liabilities, the totals at those levels are updated; when you are satisfied that they are distributed properly, you can click on the "Set Opening Balance" button, and the sum of the totals for Funds' and Liabilities' opening balances are put into the opening balance for the asset.

Once the opening balances are set correctly, they should not be changed.