I checked in my test form, and I found the same problem if the underlying table data contains seconds information. To achieve the 'hours and minutes only' effect, you need to:
-- Set short time as the format for the bound column in the table
-- set short time format for the field on the form
-- make sure there is no existing data in the table which contains seconds values. You could use an update query to force the existing data to hh:mm format, e.g.
update [MyTimeField] to:
format$([MyTimeField], "hh:mm")
When I did all three steps, I saw hours and minutes only.
Bob Stubbs