When you run a query, you have the posibility to format the fields that display the query. Normally the query get the field format from the table, so if you have a table with a Numeric field that you formmated as currency without decimals, for example, the query will result the same format, numeric, currency no decimals.
However, if you create a calculated field, giving that field its name with the alias, when you get the result, you have the posibility also to format it, and show it in currency format (for example).
Okay, the problem is that even if you save the query, it doesn't remember the format type.
This is clearly a bug, because in tables you can remember the field formatting, however in queries, when calculated fields are involved, you cannot remember the fields formatting for calculated fields. Even if you give format to the calculated fields and you save the query, you'll lose that format next time you open the query.