NEVER format anything at the table level.
WHY? - all you are doing is obfuscating the actual value and not changing anything. A prime example is with date fields. If a date field contains a time component, you can format it so you never see the time. Doesn't mean that time is not there and you'll have trouble trying to figure out why you can't retrieve the correct records when you are looking for SomeDate = #12/31/2017# and returning only 2 records when you can SEE that you have three rows with that "exact" value in the table.
Do any formatting you need in the form or report or if you are exporting a query, in the query.