Changing Field Length in SQL to accomodate export

[Brewhaus]

We need to change the field length for the OrderShipmentsID, as it is currently limited to 4. It seems that this limitation is ignored when AC generates the number, as our current numbers run 5 digits. However, this limitation does appear to come into play when exporting data from UPS Worldship into the table. We have set Worldship up to automatically export the tracking numbers into the database, but it cuts the OrderShipmentsID at four digits.

Can anyone help on this? I have tried everything that I can think of within SQL to change the field length, but I cannot get it to change.