How to: Modify Column Length (Visual Database Tools)
When you select a data type, the column length is automatically defined. You can reset the Length property for a column with a character data type, such as binary, char, nchar, nvarchar, varbinary, or varchar, if you want to increase or decrease the length of acceptable values in that column. For columns with numeric data types, the length is set by the Precision property.
To modify the length of a columns data type
In Object Explorer, right-click the table with columns for which you want to change the scale and click Design.
The table opens in Table Designer.
In the Column Properties tab, type a length for the column's data type in the Length field.
You can edit the Length property for character data types only.
The new length is assigned to the column in the Table Designer after you click outside the grid cell or use the TAB key to move to another grid cell. It takes effect in the database when you save your changes in Table Designer.