Unfortunately it has to be done manually in the database. When the authentication controls load they do so in the order that they are listed in the Authentication table. In the past I've opened the Authentication table, copied the DNN Standard login row (the first row in the table) and pasted it as a new record. Then I deleted that first record from the table. In my case I've usually only been concerned with moving the AD provider ahead of the DNN provider. If you've got multiple providers then you may have to change things around a little more so that they're in the order you want them in.