Merging Bank Accounts

My checking account was compromised so my bank had me establish a new one. I assumed I would get a bank statement for each account which I could use to reconcile each account. Instead, my bank provided me with one statement showing the accounts as combined. I tried moving the entries from the old account into the new account by dragging them from the register of the old account onto the new account name in the list of accounts. While dragging would work for a single transaction, Quicken would not let me select all transactions and drag them (likely because there are over 20,000 entries). How can I combine the accounts (or alternatively, how do I reconcile two accounts covered by a single combined bank statement)?

Using Quicken Classic Premier (Version 7.3.1 (Build 703.50428.100)) on a Mac.

Thanks.