You can change the size or position of columns in the alerts table in the following ways.
To resize a column:
Hover over the border of the column until the cursor changes. Drag the border until the column is the desired width.
To move a column:
Drag the column to the desired location in the table.
To reset the table to default settings:
Select Reset Layout from the view selector drop-down menu, as shown.

Note
Reset Layout only appears if the alert summary table has been modified from its default settings.