The cursor should turn into a double-headed arrow:

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Double-click.
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.
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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.
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Close the Customers table.
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When the alert window appears, click the
button to save changes.