budget subaccount rollup

[Steve Nospam]

Windows 7 (64) GnuCash 2.6.3

I seem to be missing something basic.  I have a budget divided into 4 periods.  I have accounts with subaccounts, for example a Medical account with subaccounts copay, insurance premiums, dental.  I recently needed to increase the budget for insurance premiums.  I increased the insurance premiums subaccount in the budget and noticed that the Medical account total in the budget did not reflect the increase in the subaccount insurance premiums.  I had to manually change the Medical account budget to reflect the new total for the 4th period.  Is this how GnuCash is supposed to function?  I would think that a budget account would automatically reflect the total of its subaccounts.  I've searched for a config change and the forum but no joy.