Change the width:

Of a single column

Drag the boundary on the right side of the column heading until the column is the width you want.

The displayed column width is the average number of digits 0 through 9 of the standard font  (standard font: The default text font for worksheets. The standard font determines the default font for the Normal cell style.) that fit in a cell.

Of multiple columns

Select the columns you want to change, and then drag a boundary to the right of a selected column heading.

o do the same for all columns on the worksheet, click the Select All button, and then drag the boundary of any column heading.