UserID inputs incorrectly

I have four fileds: first name, last name, userid and password. When adding a new record "Add New", the userid field does not update properly. Instead of updating with the userid I put in, it uses the userid of the person who logged in and is updating the database. I then have to go back and "Edit" the record to update that field a second time in order for it to work. This is when the login to manage the list is pulled from the databse itself. When I hardcode the login, this problem goes away.