hand-free line priority

[softy783]

Gigabit Color IP Phone SIP-T38G

currently when the speaker button is pressed it will default to the first registered line

any way to reassign to another line.
I moved my spa-3102 to "Line1" position but was unable to get it registered.
Of course now the T38G defaults to "Line2" a registered number.
Can DSS Key somehow be forced to default to "Line1" location?
Where are the controls for the "Speaker Icon" button?

thanks in-advance