We need to get some terminology straightened out. A table contains fields
in which data are stored. A table is an interface that lets you work with
the data. If you have a form that uses a table or query as its record
source, controls such as text boxes, check boxes, and combo boxes may be
bound to fields in the underlying table. I think you are using "field" when
you mean "control". Changing the field size in *table* design view will not
change the size of a text box bound to that field, so I am guessing that you
changed the size of the control (text box), not of the field. If you
changed the field size, the text box would accept more characters (unless
there is an input mask, code, or other things in place that would limit what
you can put into the field or control), regardless of its physical size.
Again, open the *table* in design view. You will see the headings Field
Name, Data Type, and Description at the top. The fields in your table are
in the Field Name column. Click on the field in question, and look in Field
Properties below the listing of fields. Click the General tab if it is not
selected, and look for Field Size at the top of the list on the General tab.