After you've opened the table you want to modify in Design view, click the text field whose size you want to change to select it.
The lower half of the table window shows the properties of the selected field, the first of which for text fields is Field Size. Click the Field Size text box.
Type the number of characters you want the text field to allow.
Click the Save button on the Standard toolbar in the main Access window to save your changes to the database table.
Text fields (that is, fields that use a Text data type) have a default length of 50 characters, which is usually long enough. To conserve space or to limit the number of characters, however, you may want to change the field size. For example, for a field that contains state abbreviations, you may want to set the field size to 2 so that users can enter only two characters. For longer entries (such as a street address), you may want to increase the field size.
Data Types and Field Sizes
You can change the field size of text and number fields only. Other field types have a default size, which you cannot change.