You can enter historical data for your expense and income accounts to have your Charts and Periodic Account Totals show the correct amount for previous months and years. To enter historical data, navigate to Company Menu > Edit Historical Data.

This window allows you to select each account and edit the historical data for certain intervals for the account.

Select an account on the left and then click the Amount column in the list on the right to edit a specific amount.

You can press the Tab key to navigate to the next total in the window. Intervals, as well as accounts, with historical data will appear in bold in the lists.