Hi lucy7,
You can sort the invoice list in the sales section by clicking on the headings at the top - if you click the 'Date' this will flip the order from newest - oldest and vice versa. If you select the 'Status' this will re-group the order that you are viewing.
If you are viewing the invoice list report, you can also change the format of this to show newest to oldest transactions by running the report and selecting 'Sort' > Descending order.