You can change the size of margins for an entire table.

Tip: The easiest way to resize the margins is to drag the outside margin of the table.

Or you can follow these steps:

1. Put the document in edit mode.
2. Place your cursor in any cell of the table, and click Table > Table Properties.
3. Click the Table Margins tab.
4. In the Table margin section, select Absolute (inches) or Relative (percentage) in the fields beside Left and Right fields.
5. Adjust margins in the Left and Right fields; click the check mark to save.