The cursor should turn into a double-headed arrow:
The Company Name column should resize to fit the widest piece of data in that field:
TIP: Instead of double-clicking, you can also drag column heading dividers to set column widths manually.
Double-click the divider between the Address 1 and Address 2 column headings.
The Address 1 field should resize to fit the data in it.
Click the window's button to close the Customers table.
When the alert window appears, click the button to save changes.