Can not be done you have to set all the audios then do a soft reboot for it to remember them.
A way to avoid getting audio descriptive as main audio on 28.2e is to go into 'setup', 'system', 'A/V settings' and change 'AC3 default' to 'yes'. This will stop audio descriptive on the HD channels. Also make sure 'AC3 downmix' is set to 'yes' if you are not using a 5.1 amp.