When you edit a general ledger account code the period to date and year to date balances are shown on the record window. However, the period balance depends on which open period you have selected.
An easier way is to select File|Account Navigator from the main menu which shows period activity and yearly balance up to the selected period. If you want to check the end period balance for an earlier period, just change the "period" selection from the drop-down list.
There should not be any special process you need to run to obtain end period balances.