You can see the transactions affecting Uncategorized Income and Uncategorized Expenses by running a QuickReport for the Accounts:
The Customer opening balances are entered as Invoices with an item called "Opening Balance." Edit this item and change the income account from Uncategorized Income to an appropriate account, perhaps Opening Balance Equity. Be sure to consult your accountant when selecting accounts.
From the Account QuickReport, QuickZoom (double-click) on the transaction and change the Uncategorized account to a more desirable account. Be sure to consult your accountant when choosing accounts.