Yamaha DTXpress/DTXplorer/DTXtreme

Hi,
I just got a DTXPRESS I, and I'm trying to edit the triggers, but I 
don't understand how to save the changes. When I try to save, lets say 
trigger 1, it asks me to save it to a new trigger number between 8-11 
("Store TRG to 8 Are you sure ?").
This isn't what I want to do, I want to edit trigger 1; not assign it 
to a new trigger number - especially to 8 which is already in use by 
my hi-hat.
The manual says that "You can edit both preset (No. 1-7) and user 
Trigger Setups (No. 8-11)" but it's not working for me. It is very 
frustrating because I need to adjust the gain and velocity.

Can some one enlighten me? What I'm doing wrong? 
Any insight would be appreciated.
Thanks,
Brian